I have been in here for a long time and recently i've been lurking the HF forums,so i have a few questions for those who already play it:

There's been talk of stewards for the new houses,are they just housecarls or real stewards like Proventus?What do they actually do?

Can you complete a house with less than 20000 gold?

How are the bards,how many songs can you choose?

Can you marry Rayya?

Your steward is one of your followers, they will live within your new home and you have dialogue options telling them to go collect materials for building your home, it's pretty handy to have incase you dont feel like collecting it all yourself.

You can probably build the house for around 20,000 gold. You might not be able to fully furnish it for under 20,000 but certainly build a reasonable sized home.

I've not spent too much time in my home so im not sure about the Bard options, but I assume he will be able to play all the songs a bard can play in the game.

Well, I started with about 90k gold, after three houses -- errm 25k left, I spend a lot on wood and iron (dam nails.)

I think Hearthfire would be quite fun if you started over as a poor character and had to collect everything through hard work instead of spending all our gold on it. It's definitely a good option for a future playthrough.

What about the redguard? Can we marry her? There's just one option for redguards in vanilla and she doesn't even move to your house.

I haven't found any new marriage options, but the only NPCs I talked to were in the caravans. The Falkreath housecarl is a Redguard though, so you might be able to marry her.

Nothing on her being a marriage option on UESP but according to Wikia, she can be married:

http://elderscrolls.wikia.com/wiki/Rayya

Found this small article about Rayya being the only new addition available for marriage:

http://www.gamefront.com/skyrim-hearthfire-how-to-find-the-all-new-marriage-option/

Guess you are in luck

EDIT: Confirmed on UESP too.

I guess. Always wanted to play a redguard.