In multiway pot any bet I think tells that you got that 8. I probably bet small because any raise I get it will be from TTxx 8Txx. Betting smaller in my opinion can get others to call with over pairs or straight draws. Just my fish opinion.

Especially at micros you get the best value (in terms of how wide the calling range is, not purely in $$$) on the flop, second most on the turn and smallest on the river. Reason is that majority of players don't really think about ranges or your hand, they just look at their own cards and if they can improve or not. It is easiest to get calls from draws on the flop, as there are 2 cards to come. On the turn there is only one card to come, so the chance is half of what it was on the flop (in their mind!).

To make money against field at small micros, you need to valuebet a lot. To check here you would miss a lot of value, so always bet here. Of course in terms of repping a range any decent betsizing reps 8+. But against average PLO5 players there is a psychological difference between pot and 15c. So I think that 15c is the best sizing here.

I would open preflop in PLO5. :)