Few questions:
1. Early Jan. is a good time?
2. Where to sleep? Can you recommend a cheap hotel wit A/C?
3. Good web site for info.

Windwise early January is perfect. All hotels have A/C Rooms. To name a few near the spot: Aissatou Resort, Windpia, Lazy Dog, Blue Bayou, Surfer's Home, 7Stones, Banana Saging. http://www.myboracayguide.com has good information.

Hello!
January is good time for kiting, but during New Year holiday it could be overcrouded in the lagoon. There were around 60 kites on the water last season.
You could stay direct on Bulabog beach. It would be cheaper than on White beach.
The best choice is The kitevillage www.kiteboracay.com . Butterfly garden is a good place to stay (www.boracaybutterfly.com). Windpia is also nice (www.windpia.asia/). The cheaper accomodation is Banana Saging www.boracayguesthouse.com. There are a lot of private apartments to stay but you can't book them through the internet. You can do it just on Boracay.
Some information is here www.boracayisland.org.
Kiteregards,
Vlad

Butterfly Garden has closed down.

Yep, Jan is a good time for wind.
Personally, I wouldnt bother booking accommodation in advance, there's tons of places and you can just rock up and try somewhere you like the look of. Book in for one night and then have a good look around at other places until you find the one thats suits you. Staying on Bulabog puts you right on the kite beach but there's less going on in the evenings. Staying on white beach puts you amongst the bars and restaurants. Both are very close together and easy to walk from one to the other. Just depends on what you prefer. hence, it being better to decide once you get there and see what's what.
If you are there over new year (argh!) you'll need to book in advance but I'd avoid this time.

Watch out for sea urchins!

Should i get a reef shoes?

You only need booties if you can't body drag upwind, i.e. if you need to be able to walk to your board. Everybody here pretends the water is deep and just body drags in 40cm depth to avoid the urchins. Works pretty good.

Due to other commitments i will need to postpone my visit to Boracay to late March. Is it still a good season or I'm late?

Late March is still ok. Not quite as windy as January though.

A general tip is to always check the current political stability before making plans.