.325×7 vs. .325×8 is about like 6th vs. 10th gear on your ten-speed bike (remember when they only had so few "gears"?). At 8,000 RPM it's about 35 vs. 40 MPH chain speed. If the saw is capable of pulling it that fast in the wood you're cutting, it'll cut that much faster, all else being equal. It might not be quite enough saw for that for you, but if you're inquisitive at all, the 3 or 4 bucks might be cheap entertainment. If you've got an 8t, then get a 7t to try as it'll give the saw more grunt and maybe you'll like that better.
One thing I forgot to mention is to get a file guide you're comfortable with (the stamped steel ones work well enough), and a depth gauge setting tool (I like the Oregon drop-center model). A sharp chain is safer and faster and easier on the saw. If the chain dulls in the field, you'll save more than the time it takes to touch it up then and there, and you'll be safer.
If you're very new to cutting, you probably won't do much boring, but I know you've already had to swing the tip through the log without it protruding. The RM2 tie strap makes that nearly as impossible as the nose guard Echo puts on their saws.
Will it tend to kick back more without the strap tips? I'm sure it will a little, but not as much as you might think. The tie straps don't prevent it outright.
The RS chain is much more aggressive (and about 15% faster) than the RM, but I don't think it has much more tendency to produce kickback. One thing you'll notice about it is where with RM the chain will dance a bit side-to-side while starting a limb cut in something like hickory, but the RS will get right to work. Much safer in my opinion.
They are not dumb questions at all.
You might want to investigate the good stuff at
http://www.madsens1.com/sub4.htm. Some people fairly question some of the information, but it's pretty good overall; and I think we've all picked up at least one new thing there.
It rehashes much of what's in the saw manual, but it does cover some of the more esoteric stuff the manual doesn't, so I'd recommend fetching a copy of
http://www.osh.dol.govt.nz/order/catalogue/pdf/treefell.pdf to study.
That's an extremely fine saw model you've got. What made you decide on it?
Glen