Service sizes are based on a calculation that is made according to the NEC. It has nothing to do with the age of the home, or even its size, although a larger house might have a larger service because the calculation ends up bigger.

Homes with gas appliances often do not require a very large service, but I think the smallest service the code allows these days is 150A for houses and 60 or 100A for apartments. I don't recall off the top of my head and am too lazy to look it up right this second.

Whole house surge protecters probably do a better job of protecting your stuff than the plug in units. Most modern electrical and electronic gear are pretty tolerant of the level of surges that the plug in units can protect against. It is all about how much energy the surge protector can absorb. The plug in units just do not have much capacity.

There is a lot of misinformation out there about surge protectors and even among people who one might think would know there are a lot of different thoughts on what is the "best" answer. I think the real answer is that no one really knows with any certainty, especially for residences.

One thing that is often a problem is the intersystem bonding. It is pretty critical that the grounding point for the incoming phone, cable, and or satellite lines be the same as for the structure's electrical system but it is quite common to see a seperate ground rod driven just for these connections. A very bad idea, but quite common.