I love bettas!

I'm an oddball and like the pinks, whites, and speckled (I like the blues, greens, and reds but it seems everyone tends to have those colors. Gotta be different! lol)

Right now I have a pink female.

Anyways...re: your questions:

A two gallon would be adequate--however, if you can afford a larger tank, by all means do so! Your fish will "tank" you for it! (*groan* ok, bad joke! lol)

You do not have to have an air pump/filter/etc. THEY WILL DO JUST FINE WITHOUT IT! (Mine currently doesn't have one.) However, I would recommend one. You can buy 'airstones' (I believe they are 88 cents at walmart)--if you hook this up to a pump, it will make a very pretty 'bubble' display! There are also bubble walls or wands that you attach to the back of the tank--they make for a beautiful display as well!

The fish would survive the wkend w/out food but I don't know how healthy it would be for him. If you'd like to leave him in the office over the wkend, I would suggest adding some LIVE plants to the aquarium. Not only would this supply him with a snack, it would also help add oxygen to the tank!

Good luck!