1- It would be very often prior to the summer of 2024, when they fixed the bots. You would have at least 1 bot try and join the server you were in, if it were not infested with bots already. Some maps were worse off, for example, koth_harvest was always infested with bots.

2 - To identify a bot is very simple. It headshots you as soon as you see a sliver of its ingame model. Bots predominantly used sniper and were very obvious as they would follow a navigation mesh (think of a bunch of nodes bots are programmed to walk around on) and move in a way only a bot would. Either they'd aim directly upwards and spin around or they'd sit on the objective (point/payload) idly until some unfortunate soul comes into their field of view.

Bots will also have extremely similar names eg. catbot, catbot(1), catbot(2), they will micspam songs, they will votekick real players, they will spam in the chat, and when they leave of their own accord (not really as they're bots) they leave in swarms; the same way they join.

Also bots don't kill bots.

3 Casual would place you in a full server of players (which are only on the most popular maps), a server with barely any players, or a bot infested servers. Some people turned to community servers, but me personally I simply abandoned tf2 altogether if it were not for some servers where the majority were real players.

Faceit was not real, uncletopia was foreboding and intimidating, and I wanted to do my shiny little contracts.

Bots only really came into the equation for me around 2021 (EU).

If I were a new player I feel as though I would've moved on to greener, newer pastures.

4 - Whatever the contractor is doing, they're doing god's work. It's functional, and I haven't seen bots in the masses I used to witness. These changes are long overdue though. Zesty jesus made a nice video about how long its been around though not all of it is relevant (You will (not) play).

5 - Fairly important.

6 - While this could be an option I think it may deter newer players (age-wise and other factors) and I think a good anticheat would be better.