Will i have to re-download all my mods again ?
Just drag them from your community folder to a side map on your dekstop for example, just in case. After installation is complete drag them to your community folder again
In other games updates sometimes break the mods so I guess it just depends on the updates.
In theory, no you should not have too. However, to be safe do what @AtcDude1992 has suggested (I have marked that answer as solved).
Bear in mind, updates may break mods or vice versa, so once you copy mods back into the community folder, be prepared to remove them one by one if you are having issues.
Yeah i will put them on a pen
Guys another question, this is my pc
i7 - 9700K + 24GB + RX 5700 XT 8GB + SSD 1TB +HDD 1TB
and im thinking in add 8GB ram more to make it more stable, i have 4 slots available on motherboard and i just have 3 in use, and if i have they working at pairs maybe i get better performance no?
Yep, 3 in use is not normal practice. Always use them in pairs.