I've been playing TF2 for a while now and I would like to ask if tools like paints, killstreak kits and so on drop randomly, I've checked the wiki but I didn't find anything there.
The official wiki nearly always includes this when discussing items, either saying how the item is acquired or listing where the item is found.
Paints depend on the colour. Some colours drop randomly. Others, usually those from early crate sets, do not drop and must be uncrated. All paints can be purchased from the store. A full list of colours and where they are found can be found on the wiki.
Killstreak kits are only earned by completing the Operation Two Cities tour in Mann vs Machine Mann up mode. They are not dropped randomly and cannot be purchased but are occasionally found in crates. More information can, again, be found on the wiki.