John Deere 115, rehab - fuel tank question and more...

[fiataccompli]

I recently rescued a JD 115 (probably 10-15 yrs old?) from a friend's woods where it sat for the last couple years after he bought a new mower. Besides the known issues when last run (tires that won't hold air more than 30 minutes & a steering gear that had once stripped & is maybe a bit "hacked" to work at the moment), I assumed the usual stuff of tune-up, fresh fuel, oil change, etc. This is a replacement for a Toro Wheelhorse that has what appears to be the same family of B&S engine (but 16hp)....so I figured I'd use the Toro for parts since it was running well w/ a new battery, no running/carb issues & a new starter until it threw a rod a few weeks ago. As a preliminary test, I wanted to get the 115 running w/ as many of it's own parts as possible...which have done (removed, disassembled, cleaned carb...it was surprisingly NOT gunked up but all the fuel was clearly old and smelled so). In the process of putting the carb back on, I broke the choke arm, which appears difficult & unlikely to replace...could install a manual choke using the remaining 180degree hole on the arm. Otherwise, with a helper holding the choke for a second and the tank flushed & filled with fresh fuel, it now starts up. However, it seems to run where it it holds a speed for a few seconds & then cuts out for a moment & then resumes...and repeat...which I may attribute to butterfly action on the carb (Nikki) feeling rather the opposite of that of the Toro, or simply to the fact that the tank must have residual crud in it despite having been pumped out & the fuel filter may be clogged also. Next steps I plan are...

1. Oil change/filter (of course)
2. remove tank & clean (the rubber seal from the cap appears to have come apart & fallen into the tank
3. replace fuel filter & fuel lines (should I replace the pump? it is working, but I notice online many vendors sell the filter & pump as a set)
4. Install the Nikki carb from my Toro on the 115...that takes care of the choke issue for now and it's a carb that was a known properly functioning unit 2 weeks ago

So, a few questions I have for wiser folks than me who are here....

1. is there any value (or is it ever done any more) to replacing the throttle control & choke with fully manual units (basically a lever to open/close the throttle & a pull for the choke)?
2. Is it possible to remove the fuel tank without completely removing the upper "body" of the mower? I saw a youtube video showing someone wrestling the tank out after chain-hoisting the rear of the body up & leaving almost enough gap....looks dubious, but the alternative of completely removing the upper body looks like a pain also.
3. Is the steering gear a common problem with these? I suppose if the proper repair for that calls for removing the upper body, I'm already "in" on #2 above.....

Thanks in advance for any helpful guidance!