First trip to Uruguay (Buenos Aires)

Hello all!
I am new to here and I am planning to go to Uruguay for a weekend here in the next couple weeks and I was wondering if anyone had any recommendations for places to stay and how to get there. I hear going by boat is the best/cheapest way to get there? The cheaper the better!!

I dont even know where to begin to plan a trip to there!

Any and all help woud be appreciated!!

Thanks!!

p.s. I am also hoping to renew my tourist visa while I am there, has anyone done that before? If I do a day trip to Colonia and back will that count??