Five
You can have up to 15 synchro's or fussion monsters total in your extra deck.
Roughly 160
You may have a total of 15 fusion and synchro monsters in your extra deck(renamed from fusion deck with the addition of synchro monsters)
Currently, no Synchro monster has a negative level.
who knows maybe over 50 synchros
7 rounds
In my diving club, there are no members in the US diving at the moment.
yes, junk synchron only affects monsters on the field. synchro fusionist activates in the graveyard.
No, Synchro material must be face-up.
the best way is to get the "machine emperor" cards which are a bunch of anti-synchro union cards
65 rounds a second and as many as 500 rounds in a burst - there is no "per minute"
No, you do not 'tribute' the Synchro Material for a Synchro Summon. They are sent to the graveyard, not tributed. You can tribute an opponents synchro monster for "Assault Mode Activate!" to summon the assault mode monster from your deck.