From what I gather from the screenshot you accidentally switched maps with e.g. /map mp_shop instead of /rcon map mp_shop. Doing the command without RCON lets you host and enter your own (local) server. That server isn't using 1fx. Mod, hence you cannot do addbot or any of the other 1fx. Mod commands. 1fx. Mod is supported as dedicated server only.
As for your weapon problem, open up the bot file and tweak the weapon weights accordingly. I created a default set for you, here:
It's not perfect, but if you are running INF with semi-default settings this will cause most bots to spawn with an AK47 and some with a M590. Tweak accordingly.
As for the bots freezing in the server, this is a known issue that I haven't bothered to pick up yet. The bot code in 1fx. Mod is almost fully vanilla right now, causing some bugs here and there. This is still on the to do list for later. I also don't know how the Demo version handles bots engine-wise. There has never been bot support in MP TEST before 1fx. Mod.