Advance CMS – Please Help 8)

Hello dear people 8)

I will be making two different sites and need some help:

The first one is a magazine site with the following functions:

CMS (text & picture)
Some articles will be free to read, but some will cost 5$ to read but then they will also be able to write and publish there own articles (with a letter limit). This 5$ offer will last for 30 days starting from the day the customer payd.

My second project is a buy and sell site that needs the following functions:

CMS (text & picture)
All ads free to read but costs 3$ to publish (publish with text, picture and attribute fields like price etc). Also the ads needs to be removed automatically after 3 months.

Obs! Payment for both sites will be with sms, tel call and credit card.

So what I need to know is:

Are these two sites possible to make with Joomla and/or WordPress
And also which is better for my requirements: Joomla or WordPress?
And last are there modules for these functions that I require

I will be for ever grateful if any one could please answer my questions and perhaps give me some hints and perhaps links!!!

Best regards
Thomas