Welcome.
Interesting question you pose there. You seem torn between hobby and investment.
There are no rules as to what you can or cannot collect and certainly no numismatic police. Collecting comes from within. If you like them and want to collect more of the same - do it. If you want to collect but not the things you have shown us, then selling or spending those would free up funds to buy something else. Coins from circulation are not typically worth more than face value however, as they rapidly get knocked edges or other contact marks and so lose any premium attached to the coin in mint state. there are a few exceptions, but not a lot.
It is impossible to say what the error is on the E, but if a blocked die then this is part of the normal wear and tear experienced by a die.