You can’t buy ships directly through the cash shop, don’t know where you got this from.
Players don’t fight fair. Learning how to deal with that is part of getting good at the game.
Multiboxing isn’t cheating. It’s not against the EULA, you can do so without having to spend more money on the game, and if steam user system specs are any indication, the majority of Eve users have hardware that can do it. The only place where we might get into a grey area is when people start multiboxing lots of accounts, as that’s something that players with less powerful computers and slower internet speeds can’t do.
Anyway, multiboxing does offer several advantages, but you don’t have to do it if you don’t want to. You can still make good money as a solo player, and at the end of the day, the single biggest determining factor to fight outcomes is still player skill. It’s not about how much money you spend, or how much isk grinding you do. If that were the case, carebears would be the kings of New Eden instead of food for wolves.
Also, you might want to check out this corp. They might be something that you would like.