New Boat Questions

Two questions:

I will be selling my 14' aluminum boat which has front and rear bass
fishing decks in the next few weeks and then start looking for a larger and
better aluminum bass boat. I am really looking at Bass Tracker as they are
popular, nice boats, and easy to find. I'm will be looking for a used (5-15
years old) 17' 175. I'm looking for a 45hp-70hp engine. Anything larger
would drive the price too high for me. I want to stay away from the 25hp
engines as I don't think I'd be happy with it (I've owned an 18' aluminum
Grumman with a 90hp engine and am 18' Procraft with a 150hp engine). I don't
mind the boat running 25-30mph with 2 people.

I live in Florida and like fishing smaller lakes (Harris Chain, Butler
Chain, and sometimes Kissimmee... but near shore). I'm looking to spend
about $5k. Any comments?

Another thing I _really_ want is to have a depth sounder. I find that fish
finders are about useless for high-speed passes to find holes. They are just
too slow. With a sounder I can locate them and then go back with a fish
finder. Would you all agree/disagree? I will probably need to add this item
and won't have a lot of money left. The boat will probably come with 1-2
fish finders. Would I be better to buy just the depth sounder or a fish
finder with a digital one built in?