Вопрос: Как получить значение атрибута элемента XML который нужно так же найти по атрибуту?

Лучший ответ: Можно использовать SimpleXML (он нередко уже идет в зависимостях)
Инициализация:$xml = new SimpleXmlElement('<ElementList> ... </ElementList>');
Поиск искомого элемента (берем первый попавшийся):$element = $xml->xpath('Element[@Name="TRF_CL_BASE"]')[0];
Значение (можно заменить на int, если нужно использовать как целочисленное значение):$value = (string) $element['Value'];

Худший ответ: Используй:simplexml_​load_​filesimplexml_​load_​string
Массив будет иметь вид:SimpleXMLElement Object
(
    [Element] => Array
        (
            [0] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 2235961003
                            [Name] => OSAGO_FR_CARCTG
                            [Value] => 8244
                            [Save] => N
                        )

                )

            [1] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 2235961103
                            [Name] => OSAGO_FR_AGRPERIODM
                            [Value] => 12
                            [Save] => N
                        )

                )

            [2] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 2235961203
                            [Name] => OSAGO_FR_USEPERIOD
                            [Value] => 12
                            [Save] => N
                        )

                )

            [3] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 2235961303
                            [Name] => OSAGO_FR_MULTIDRIVE
                            [Value] => 0
                            [Save] => N
                        )

                )

            [4] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 2235961403
                            [Name] => OSAGO_FR_TAXI
                            [Value] => 1
                            [Save] => N
                        )

                )

            [5] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 2235961703
                            [Name] => OSAGO_FR_SBJTYPE
                            [Value] => N
                            [Save] => N
                        )

                )

            [6] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 2264076003
                            [Name] => OSAGO_FR_TARIFFZONE
                            [Value] => 3401214003
                            [Save] => N
                        )

                )

            [7] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 2496138003
                            [Name] => FR_KE2
                            [Value] => .93
                            [Save] => Y
                        )

                )

            [8] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 2685741203
                            [Name] => KVS_OSAGO
                            [Value] => .93
                            [Save] => Y
                        )

                )

            [9] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 4655146503
                            [Name] => FR_USEWITHTRAILER
                            [Value] => 1
                            [Save] => N
                        )

                )

            [10] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 761850500
                            [Name] => TRF_CL_BASE
                            [Value] => 7399
                            [Save] => Y
                        )

                )

            [11] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 761851700
                            [Name] => TRF_CL_ZONE
                            [Value] => 1.8
                            [Save] => Y
                        )

                )

            [12] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 761851800
                            [Name] => TRF_CL_BONUSMALUS
                            [Value] => 1
                            [Save] => Y
                        )

                )

            [13] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 761854000
                            [Name] => TRF_CL_POWER
                            [Value] => 1
                            [Save] => Y
                        )

                )

            [14] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 761854100
                            [Name] => TRF_CL_PERIOD
                            [Value] => 1
                            [Save] => Y
                        )

                )

            [15] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 765909400
                            [Name] => TRF_CL_ABUSE
                            [Value] => 1
                            [Save] => Y
                        )

                )

            [16] => SimpleXMLElement Object
                (
                    [@attributes] => Array
                        (
                            [Isn] => 816328000
                            [Name] => TRF_CL_MULTIDRIVE
                            [Value] => 1
                            [Save] => Y
                        )

                )

        )

)