The right commander is probably Imodane, the Pyrohammer, who can spread your Burn spells out across all of your opponents to speed up your clock, but Ojer Axonil is a great alternative
As youre looking to win through combat damage, Equipment like Nettlecyst and Fireshrieker are automatic inclusions
You cannot choose new modes
For example, it wont affect Flameblast Dragons cost, since thats a cost paid when a triggered ability resolves, and it wont affect a kicker cost, since thats an additional cost to cast a spell
Replacement effects that modify the number of counters being placed on creatures you control, such as the effect of Branching Evolution, apply to this ability as normal