A Synchro Summon is a special summon, so the summoned monster can be in attack or defence mode, just must be face up.
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.
No, a Synchro Summon is a kind of Special Summon.
Yes, you can, as a Synchro Summon is a special summon, you can perform a Normal Summon on the same turn as one or more Synchro Summons.
Somewhat, yes. A synchro does not count for you Normal Summon for the turn. This means that you can do multiple Synchro summons in one turn. But if you are implying that a Synchro Summon can be usd for a card effect triggerd by or that needs a special summon, then a Synchro summon will not count. ^That's a bit vague. Synchro Summons will most certainly trigger/count towards effects that look for Special Summons - case in point, Bottomless Trap Hole, which can respond to a Synchro Summon because it is a kind of Special Summon. Special Summon is the default, and then you have special types, like Fusion Summon and Synchro Summon. Anything that looks for a Special Summon, will trigger from any of those. However if it only triggers from a Synchro Summon, then only a Synchro Summon will do, not a regular Special Summon.
Yes, Tokens have a level and can be used in a Synchro Summon.
yes, junk synchron only affects monsters on the field. synchro fusionist activates in the graveyard.
No, Synchro material must be face-up.
No. A Normal Summon is face-up ATK mode, a Set is face-down Defense Mode, and a special summons can vary from face-up attack, face-up defense or face-down defense. No card can summon in face-down ATK mode, however the card Darkness Approaches can flip an ATK mode monster face-down without changing the battle position.
The levels of the Synchro Components must be exactly equal to the Synchro Monster you wish to summon. So for a Lv8 Synchro, you must send 8 level's worth, no more, no less.
You are allowed to use Monster Reborn and similar cards, under most circumstances. The important thing is that the Synchro Monster must have been properly special summoned first. If the Synchro Monster ever goes to the graveyard without being properly summoned by Synchro Summon (ie, Starlight Road can do this) then the Synchro Monster cannot be revived like that. Similarly, if a Synchro Monster had its summon negated, it also can't be brought back from the graveyard. Last thing to consider is some might say "cannot be special summoned except by Synchro Summon" meaning the only way to summon it is by Synchro Summon, there is no other way, even if it was properly summoned first.
Currently, no Synchro monster has a negative level.
All Urgent Tuning does is let you perform a Synchro Summon in the battle phase, apart from that, all the regular Synchro Summon rules apply. Synchro Summon components must be face-up on the field - Urgent Tuning does not change this.