Just a little advice. You shouldn't be betting looking at the pot size preflop. You should be baseing your bets/raises on the size of the blinds. For instance if the blinds are 25/50 and you bet the pot 75 it costs the small blind 50 to call a 150 pot. That's 3-1 odds
and an easy call with almost anything. Your bet should have been more like 3-4 times the BB, in this case 150-200. This makes it harder for someone to call with 3-5 although you will still see some do it. The reason people call with hands like 3-5 is because if they hit they know they can get someone with a large pocket pairs entire stack. I do it myself depending on my read of my opponent, my position, how many people are in the pot, my chip size, and the cost to enter the pot. Don't think because someone played with "crap" is was a bad play, instead think about if you made any mistakes in the hand. Here I see 2. 1) You didn't raise enough pre-flop to make him pay to play speculative hands like that, and 2) You fell in love with your Kings and didn't think they could get beat. It's one pair and beatable no matter how pretty it looks.
The push with 10s was fine, it's what you are supposed to do with a med pocket pair and a low M. You want a caller, you just got unlucky, doesn't mean the play was bad.
One should play the low stakes to learn the game and have fun. I hope you do both. Congrates on the overall play though, don't worry about the losses they happen to everyone. Well I shouldn't say don't worry, worry if you aren't learning anything from them.