If your passion is fishing which it sounds like it may be, and you think you ae going to get into it big time then I would look for the boat that is all set up, with down riggers and all, there may be a deal out there just for you just remember most fishermen are in love with their boats and rigging so most want top dollar so they can up grade to the next level.
As far as size, you will never here to many fishermen talk about having a boat to large, but you will find fishermen talk about their boat being to small and wish they had the next size up, if you are thinking 17 to 20 feet is the right size for you, go 20 to 21 feet, aluminum of course, ease of towing and maintenance.
I/O vs outboard, most fishing guys go with outboards, again less maintenance, easy upgrade to larger engine. One suggestion i would make if the pocket book can handle it go with the largest engine possible, it very easy to be sold under powered boats just because of price, then when you go to run the boat and you find out its a dog out of the hole ooooooh your so pissed and it hard to enjoy the boat after that.
I/O vs outboard, one thing to keep in mind is the use of the stern of the boat, the outboard engine is in the way for some fishing guys ( not many)to line up their down riggers and poles.
( YOU MAY ALREADY KNOW THIS)
If you think you are going to enjoy fishing and boating but just not sure, then i suggest go simple and up grade from there, true boaters are very impatient people (can be helpful also) and you will need to get an understanding of that at the dock, make sure you have your boat ready to launch, poles in place, food on board, passangers ready on standbv, parctice backing the boat to the ramp on a rainy day several times so you have it down patt for the sunny busy days The dock can be, or is the most frustrating place for boaters, there are more husband and wife fights at the dock ( and if you dont beleive me go to any busy dock on a four of July, and take a video camara, cheap entertainment ) And if you have a girl friend or wife that can back a boat down the ramp successfully AWESOME!
BUT PLEASE DONT FIND OUT SHE CANT ON THAT SUNNY BUSY AFTERNOON, PLEASE DONT DO THAT TO HER OR THE BOATERS STACKING UP BEHIND YOU!
( AS I SAID YOU MAY KNOW THIS )
ENJOY YOUR BOATING SEARCH! :rock:
REMEMBER AS THE WINTER WEATHER STARTS TO FADE BOAT PRICES GO UP!
GOOD LUCK!