Event advice for newcomer.

Just started a week ago. Got lucky picking up the Death Ray card and got the Golden Tower as my first Ultimate. Now I've made some decent progress on the current event but I have no idea what is worth my tickets (or if I should just save them, do they carry over?)

No idea how relics or bots work. It'd be nice to have some fresh music but that seems a bad investment 😆

Also if y'all think I'm doing something grossly noobish or wish you'd known something when you first started, feel free to share! Thanks all!