If the engine is broken in, and you have it tuned right (not too lean) it should be safe to drive it like you want to.
As for spare parts, their are some you will most likely need at any time. (listed in order of priority) Also depending on how hard you are on the truck.
- extra battery for plug warmer/ignitor
- glow plugs
- extra spur gear
- extra turnbuckle
- extra set of A-arms
- Healthy assortment of zip ties
- double sided sticky tape
As for needed items
- decent air filter (motor saver)
- fuel filter
- after run oil
Good tough parts
- Lunsford Titanium turnbuckles
- RPM shock towers
- RPM A-arms
- Robinson racing steel spur gear (driver preference.)
Any other parts(and the good tough upgrades) you should just upgrade as you break them. You will find the first things I listed to be commonly needed items that will end a bash session abruptly.
These cars nickel and dime guy hard. I have more than once spent the last of my R/C budget on an upgrade, only to break a different part the next day. Then I am stuck with some cool upgrades, but not enough cash to fix what I broke. That's why I suggest upgrading as you break instead of blowing your load on hop ups right off the bat.
Since this is your first car, here's a tip or two. To help avoid frusteration
Before you even start it, check all the screws for snug. Second tank of break In I lost my pull starter. ABout the third time out, my motor m,ount screws came loose, and I ate a few spurs before I figured it out.
If it's cold out, warm up the engine before you try to start it, either with your car heater, or a blow dryer. Cold engines don't start well. They can fursterate the heck out of you.
Always run with the lid on. I found out the hard way. The lid really helps protect the valuables inside. Again more than once I thought "ill put it on next pass", and promptly rolled it and broke parts lol.
Cut a hole in the windsheild if their isn't one already. You need good airflow over the engine to keep it cool.
Good luck, you found a killer site with lots of info.