I assume this is the boat model you're looking at:
Fish N Sport 510 Pontoon Boats Mid Mini Pontoon Boat Compact Small Aluminum Marine Inflatable Rescue Bass Crappie Catfish Fish Trolling Lake Front Pond River Fishing Fisherman Private Personal Looks to be an awful stable platform to fish from if that is your major concern. However, at 60" wide, pretty much any boat will be. Before you buy, consider the resale value on a boat like that. If in your area, something like that is pretty common, that's one thing. However, around here, I think you'd take a beating if you decided to sell.
That being said - Any of the following will give you the performance you want in shallow water. Don't think you'd be disappointed in any - Black and White - Eagle 320 or 480. H'bird 565 or 575 or if color - Eagle 500C, H'bird 585C. Any of these will do, but as you get more expensive, the resolution is better (more pixels per square inch of screen) giving you a less grainy picture of what's down there. If you jump to color, you'll get a good quality pic, but you'll also be able to tell the bottom composition a little easier as the color is a little easier to read in that regard at least to me. This can be pretty important if you're searching for brim beds.
On the trolling motor, before I went with a 12volt motor, I'd ask the factory. I'm sure in most situations, you'll be fine in that boat, but those pontoons are gonna have a lot of drag, so I wonder if the 12V will propel it at a good speed and just how long a good battery would hold up especially in the wind. At the very least, I think you'll need 2 batts wired for 12V to be able to fish for as long as you want, especially after the batts get a little age on them.
The TM you listed has the universal transducer. You can get an adapter for any popular fishfinder like has been mentioned for something around $20.
On the trolling motor, I assume you've decided you want remote and wireless steering. However, it seems to me that with that set up, you'd be just about as well off with a hand control as 80% of your time is going to be spent in the fishing chair right in front of the trolling motor mount. On top of that, you could get a 24V Maxxum 42" hand control in the neighborhood of $520 or even $360 remaned from here:
New Page 1. You might want to check the recommended shaft length from the factory though. Looks like a 42" would be fine from the pics, but I'd double check that from the factory.
As far as batteries go, I've always heard good things about Trojans and AC/Delcos, but never owned any. My most recent battery was an Interstate and seemed to be holding up good, but I just sold the boat, so I can't comment on the longevity after only having it for 1 year. Other than that one, all I've ever owned were Wal-mart Specials or parts house specials.
Anyway, just some food for thought. Hope you enjoy your setup.
Wannabe...