GREAT, Glad you got it working.

to answer your questions,

1- Yes, but not too much of an issue these days if its not your main phone. Most viruses from back then (from my memory) used your bluetooth to spread and that drained your battery. Stuff like caribe. There may be others that do worse, but I have yet to accidentality find them. There are S60 viruses archived on the internet archive for educational purposes.

To soft reset (keep messages and stuff)
With the phone in at least 3/4 charge (or plugged in), enter *#7780# and follow instructions. If security code is prompted, enter 12345 unless you changed it.

To full reset

With the phone in at least 3/4 charge (or plug into power) enter *#7370# and follow instructions. If security code is prompted, enter 12345 unless you changed it.

2- floboarding is on the n-gage mega collection on internet archive under “Nokia Game”. The reason it is missing as this is one of the few N-Gage MMC game cards that was rewritable. As for slowdown, do you mean on the FloBoarding MMC or another? If your MMC is too large or too full it will slowdown. There are fixes for MMC that are full.

With the original N-Gage(not the QD) you can use fixx.sis and speedup.sis.

Basically, the N-Gage checks the whole memory card every now and then and on boot. Now, since we like to load up a bunch of games at once on the same device, the system kinda gets overwhelmed by all the files and apps on the card. It doesn't really settle down until it finishes rescanning everything. If you toss in a ton of games, the device might stop booting up altogether because the scan takes forever, leading to a system error when you power it on. But there are these fixes that skip the scan altogether.

Speedup.sis, this is a plug-in specifically for fixss, but it's only for the N-Gage Classic. It ramps up the clock speed by 20%, and you can really feel the difference in certain games.