The fifth weapons skill, Demolitions, costs 1000 skill points instead of the 2000 required for the other weapons skills, is useful but not required to use LAMs, gas grenades and EMP grenades. Without Demolitions you can usually expect to be caught in the blast of whatever you throw unless you immediately backpedal away after throwing it. Unless you primarily use explosives, Demolitions isn't an important skill. Environmental Training is absolutely useless so far. Don't sink any points into it.
Computers is extremely useful on certain maps and completely useless on others.
When used in conjunction with Cloaking and Radar Invisibility on the Cathedral map players can effectively dominate all turrets. However, since turrets can be easily disabled by Radar Invisibility or an EMP grenade it's not recommended to choose Computers as your first skill. Multitools and Lockpicking are fairly similar - they speed up the process of getting neat stuff, such as medikits, LAMs, and secondary ammunition for your weapons, like the 20mm HE grenades for the Assault Rifle. Usually Lockpicking is used for goodies and Multitools is used for allowing access to the RepairBots for bioelectric energy recharges. If you tend to prefer straight combat with normal weapons, get Multitools as your second or third skill to keep your augmentations going.