A seller can ask for payment within any timescale they want however they cannot do anything about non payment until 4 full days have gone by and even then they can have to open a dispute and wait another 4 days before closing it. The exception is items with instant payment required, for those items you have to pay straight away, the item is not yours until you make the payment and can be purchased by somebidy else if you do not pay straight away.
It is up to a seller if they show questions and answers at the bottom of the listings. I rarely display them as the information is usually in the listing and \i don't want the prospective buyer to display their numptiness to the world 
I have often asked sellers questions and I actually prefer for them not to show up. I never ask numpty questions and I figure if it doesn't show, then let other buyers work hard for the extra info.
Is it just me, or does 2 hours seem like an awfully quick payment deadline. 2 days maybe I could understand, but 2 hours when something is up for auction is a bit rich. I would be annoyed if I were a potential buyer. I usually do pay with paypal as soon as possible, but with an auction, not everyone can guarantee being online within those 2 hours. It's unreasonable to expect it.
Now some people in here have said we have to realise the seller might not be on the computer 24/7 so people should wait a reasonable time frame for a reply-and I agree with all that- but if a seller can be granted a few hours or even a day or two's grace to reply, then they should extend the same courtesy to buyers.
I know sellers can ask for whatever conditions they like but I can't understand why they would put buyers' backs up right at the start, if they didn't have to.
