If the player actually posts the blind as stated then the seat gets cards whether he is at the table or not.
Your question about the button comes up in this first scenario as well as the second one you pose but only if the player is still away from the table after his small blind hand. Here is how it would work: ( if he made it back in time for the next deal he would get the button and play would move normally)
Player A: On button
Player B: SB - posts and leaves the table. every seat gets a hand pot is pushed and the button moves(if player returns immediately)to the seat of player B
Player C: BB
Player D:
Player E:
But let's say he didn't come right back, then with a moving button the play would be like so.
Player A: he's cool
Player B: no hand - no button - the button is moved past this seat to player C
Player C: Now has the button ! BUT he still has to post his small blind!
Player D: posts his BIG BLIND like as if he
Player E: posts a big blind
Yes, two small blinds and one big one. After this hand then life is on track and we move on. The player that posted his small blind and left the seat can take a hand anytime he returns to the table without having to post.
But now the next hand:
Player A: still cool
Player B: maybe he post and takes a hand (or gets a hand if he posted his small blind)
Player C: He's cool
Player D: Post a SMALL blind
Player E: Posts a SMALL blind as well
Player F: Post a BIG blind
After this the button and blinds are correct and play moves normally
The player that gets up from the small blind WITHOUT posting makes the button move and blinds posted as above and it does mean that when he comes back to the table he must post or wait for the BB to come back to his seat.
Just remember SMALL BIG BIG then SMALL SMALL BIG and you'll see what's happening. everybody pays.
Of course, some places just move the button past the empty seat and have the players in the new SB and BB positions post as normal. it speeds things up a bit even though it allows one player a FREE or CHEAPER hand.