Yes the LSN is definitely rich. That is why it's in the first portion of the acceleration. Also 3 turns should be WAY too much. I believe mine is more at about 2 or maybe 1 3/4. The pinching the fuel line test works pretty well for figuring out your lowspeed adj, but be sure you are doing it close to where the fuel enters the carb. If you do it too far away it's just burning the fuel in the line. But I've found when you are doing it close it should take about 3 sec to die. That will get you close to where you need to be and then you can fine tune it later if you need to.
I can't say enough how good of a car this is. I am pretty new to the hobby but I do a LOT of research on things before I step in or recommend. I started with a smartech which has been fun and helped me get into the hobby cheap and see if I would enjoy it, I have an OFNA 9.5, and the Himoto Torpeda Pro (.27 engine). I can honestly say the Himoto has been the best of them. The OFNA I've had a lot of trouble with but didn't buy new, but I do have it going now and it drives no better than the Himoto. The Himoto has just as solid looking parts. The shock towers are thinner on the Himoto BUT they are the SAME size as on the Kyosho 7.5. I've flipped end over end (having it hit once bounce up 2-3ft, and continue to flip several more times) I've had it cartwheel 6-7 times in a row on a single spill etc and so on, and have NOT broke ONE piece. I know I'm due. Because I hear people with their $700 Hyper 7 and Jammin's breaking things eventually too. But so far I have not been nice to this thing at all and it has not let me down.
A thing to remember (for everyone thinking of buying one) about the people who buy other cars and bash these because they don't' know about them. Imagine you just spent all this time thinking about buying a car. You went with one that was $500-700 because you weren't sure if another one was going to be good. So know you have your wonderful new car and someone asks about a $250 car and if it's good. Of course you are going to say !QUOT!no, it sucks!QUOT! and bash it because you have to rationalize your purchase to yourself, or you would feel like you wasted $250+.
Finally on the flip side, are their better cars? Yes. For the money? I really believe no. For a little more money? Probably not. If you want to spend $700-$1000 then of course you will get a better car. As things lie in the subtleties, but when you're a newbie you don't even know yet what you are going to need.
Great beginner car for sure and be sure to check out Laughing Potato's post about winnin 6th place in competition with his. This isn't just a bashing car if you know what you are doing. This was his first go in comp with a buggy I believe. Used it STOCK vs everyone's $1000 cars.
Last 2 issues you asked about - Parts you can get fairly easily from several on-line vendors at this point and they are competitively priced (Most of the time my Hobby shop doesn't have the part I NEED and has to !QUOT!order!QUOT! it in for a week. I can !QUOT!order!QUOT! it myself without traveling to the shop).
Lastly - I don't know yet about the Kyosho parts and others mixing because I haven't broken anything. When I do I'm going to see how the Kyosho stuff fits. I can say this - I was at the LHS and saw the 7.5 side by side and these things looked almost exactly alike. The front arms are different, but other stuff looked like it would be exact fit but I DON'T know yet. OFNA Wheels and tire nuts fit
Good luck man - hope to see you in here adding info on what you can do with these things. It's growin all the time.