Having second thoughts about the turn. My initial thought was that the turn should have been raised, then I reasoned myself out of it, and now I'm getting back to it. Not for value though - but as a bluff.

Your flop bet is a bluff - the turn is unlikely to have improved anyone which makes it a good card to two-barrel bluff on (I think - I suck at finding good two-barrel bluff spots but right now looking at it it seems ok). If you do that, just remember that you're not playing your 55 for showdown value but have turned it completely into a bluff.

It would have to be read dependent. If the opponent here is a calling station you can't bluff the turn, and if he's weak-tight you have to bluff the turn. A weak-tight player here will fold out any pocket pair and any unpaired overcards continuing only with 4x and Jx - for a weak-tight player the $0.04 means "please don't make me pay for the next street". If you did bluff a weak-tight player, he calls and leads weakly on the river you have to call (not raise) because his range then is not much wider than 4x/Jx. If you (wrongly) decide to bluff a calling station and he calls his range on the river will still have lots of pocket pairs in it and you just raise until all the money is in the middle.