keep the rust...
the ugli-er somethings looks the less likely it will be stolen or vandalized. (experienced, yes. I Am)
1. corded 3/8" variable-speed cheapest Blank and Decker or Skil drill made*... and an extension cord!
-used as much as you're likely to use them they should only last 20-30 years or so.
+good carbide or titanium coated drill bits. I find on metal work for bike/trikes I mainly use an 1/8" bit followed by a step-bit (multi-sized drill bits in 1/8" 'steps') ymmv
+screwdriver bits...#1, #2 Phillips and a couple sizes of flat blades are a good beginning- also handy in yer described battery-powered drill (all it's really good for, apparently)
2. a grinder, such as the least expensive Harbor Freight offering + metal grinding wheels and cutting disks
...that's about all you need for metal work but you might also find a saber saw and a belt sander handy along with their blades and belts.
3. Wrenches - A cheap set of SAE and metric wenches will set you back all of 20 bucks- lasts forever...Sockets and drivers if you "feel the need" Again the least expensive 6-point socket set will last forever- and get a drill adapter for the sockets.
4. hammer......... bigger IS better LOL
5. I personally like multi-bit screwdrivers but I suppose your leatherman is a suitable sub. I just happen to hate leathermans, their copys and the rest of the swissknive-like tools.
6. Hex wenches I like the multi-hex wenches. Get the metric-sized and maybe eventually an SAE (which you'll likely never use on a bike or trike
with these tools you can build/fix anything mechanical including bikes. build a house, whatever- just add raw materials as needed.
total cost ~$200 smacksers
*Battery drills have come and gone from my life but my 30-year old Black and Decker and 25-year old Skil drills drill on and on and on
and lol with a 20A controller and a 48V battery you don't really need a pre-charge resistor setup. A switch works and is mindlessly easier to use... but that's up to you
If you already bought the whoopee-doopee circuit breaker I suggest you use that since you already own it.
I use a CB for one of my batteries because I have already had it -makes a good switch (why buy another switch HAHAha ohh)