3rd night free / free night certs can generally only be used towards "accommodation only" rates (i.e. no rates that include breakfast or the all-inclusive rate), but you can certainly use them in conjunction with discounted rates. However, most hotels won't allow you to use free night certs in conjunction with xth night free promos (i.e. you couldn't combine a free night cert with a 4th night free promo and end up paying 2 nights, but you could of course combine a free night booking with the 4th night free promo and end up paying 3 out of 5 nights).

Some hotels will allow you to use free night certs with package rates / all-inclusive rates if you pay the difference between the package rate and BAR, but you'd have to check with the property, since it's up to each hotel whether they do this.

Suite upgrade certs are usually only valid for the lowest suite upgrade category, or sometimes the lowest two suite upgrade categories, but definitely not the speciality suites. You should find some recent info in this thread.

Id personally probably book the "Sizzling Savings" package at $309 incl. $100 daily resort credit, either for all 5 nights or 4 nights and use a free night for the last night. Since you're likely going to spend some money on food/drinks anyway, the nightly rate would effectively be $209. The all-inclusive option would obviously only make sense if you expect to spend >$320 per day on F&B.