I'll cover the stuff by item
1. Cut Grass: Between the belly mower and brush hog you have that covered.
2. Gather leaves: Just get a york rake or something like it from Agri Supply. May not get everything, but should be close.
3. Plow Snow: Tough one, unless you are up north, those 140 front snow plows are few and far between. Down south, there are lots of 140's but none have snow plows. I know one gent who has one and I have been working on him for two years to sell it to me. He doesn't use it but it just sits on his tractor rusting (but if I were him, I probably wouldn't sell either so I'll just wait).
4. Drag Things (get a boom pole, give you more drag/lift options), not very expensive at Agri-supply
5. Log Splitter (I think northern tool as a PTO driven one)
Having a 3 point, you should be good to go on finding stuff. The only caveat is you may have to play with PTO shaft length sometimes but that will be implement dependent. I have an adapter with a Fast Hitch Prong so I an alternate between 1 pt equip and 3 pt equip.
I would NOT get a bucket loader for a 140, for the following reasons
1. It take a lot of work to get it on (as it has took into your hyrdaulics and a stock 140 isn't set up for it so there are some mods you'll have to make.
2. Once it's on, you'll never take it off, because from my understanding it usually takes a day to put it on in the first place. Go to YTmag and do a search of the Farmall Archive and there are many folks who have had them or seen them and recommend highly against them.
3. 140s were made for farming and as a loader tractor, it stresses them highly. They buckets is usually very small and underpowered compared to modern tractors (hydraulics were very simple back then). So while it might move mulch, moving earth is a riskier proposition and can even break the chassis in some cases (as stated by Hugh McKay on YTMag board).
4. They are hard to find and expensive. I have seen them on ebay for $1-2000 dollars and if you are missing one part, you'll be hard pressed to know you are even missing something.
Now that being said, I haven't had one so this is just the collection of opinions from other folks. I thought about getting one for my tractor but after I did my research, was thoroughly disuaded. That being said, I do know a guy who said he has one so I know they are around. Good luck on that decision and if you get one, let us know how it goes.
As for the zeroturn mower, I don't have one and they seem pretty handy. One nice point about these Farmalls though is that you can independently lock the left and right brakes so it doesn't help alot to get tight turns (but not as nice as a zero turn mower).
Cheers
Ramon