Processioning a Madman
Do exactly what it says on the card, in the order it says it. So: 

Procession says you may play an action card from your hand twice. You pick Madman.

You play Madman once. You get +2 actions, and then return it to the Madman pile. If you do, +1 card per card in your hand - you did, so +3 cards.

You play Madman a second time. You get +2 actions again, and try to return it to the Madman pile, but you can't - it's already there. If you do, +1 card per card in your hand - you didn't, so you don't get any cards. (This kind of situation is exactly why it says "if you do".)

Procession says to trash the action card - but you can't, since you don't have it anymore. Oh well.

Procession says to gain an action card costing exactly one more than it - you try to do this, but the Madman costs zero, and there probably isn't anything that costs 1, so you don't gain anything.

So adding up: you get +4 actions, +3 cards, and the Madman is back in the pile. (That wasn't one of your suggestions.)