Husband being younger than wife will generally not cause any medical problems for the offspring. This is mainly a social issue. Advanced maternal age is in fact a greater risk; however, if the babies have a normal physical examination, no dysmorphism, and a normal nervous system, don't worry about it. Similarly, advanced parity (5 pregnancies) may affect mothers health, and may result in intra-uterine growth retardation; but in your case twins with weight >5 pounds is not a concern.
2. The twin babies are slightly preterm and underweight. But 5 pounds BW is generally associated with very high survival rates if no other complications. They need close monitoring of weight, nutrition and prevention of infections.
3. Regarding obesity and high BP in the mother, please contact your family physician and obstetrician about diet, exercise regimen, and if necessary medications.