Translation:If I had a keyboard, I could use this computer.
I'm quite used to seeing the particle "ĉi" come before its corresponding correlative when reading/interacting with other Espernatists out in the wild, but this particular set of lessons has tended to be more liberal with its ordering. What are the rules governing when/where/why to break the norm on "ĉi+x"?
Someone please correct me if I'm wrong, but I don't know of any rule that governs whether the order ought to be tiu ĉi or ĉi tiu --- it seems to be just a matter of preference, not of differing meaning. Maybe the ĉi tiu order is simply "winning" these days. (I share your impression that I think I've seen more ĉi tiu than tiu ĉi)
Yes, the order for ĉi with ti_ words is free. But if you want to use it with an adverb it must be before the adverb and with a “-” in between: ĉi-matene, ĉi-lunde, ĉi-nokte.
You could say "tajpilo", but that could also mean a typewriter. It's simply something to type with.