To my understanding, creatures cannot attack or block, or activate tap abilities until summoning sickness ends, so IF it ends during the opponents upkeep, I should be able to say, block a creature with a creature I summoned last turn right?
2) You can still activate abilities that aren't tap abilities the turn a creature is summoned, right?
3) If the answer to 2 is yes, you can activate abilities that require the tapping of things when it isn't considered a tap ability, say with Grand Architect , right?
the answer to 1 is summoning sickness ends when the creature sees its first untap step (under control of the person whos turn it is) so if you play a creature it has summoning sickness until your next untap step
the answer to question 2 and 3 is yes you can use abilities immediately that dont required tapping another example being Jhoira of the Ghitu
just to clarify blocking is not affected by summoning sickness either a creature with summoning sickness can block if it is untapped
Summoning sickness ends at your next upkeep.
Everything comes into play with summoning sickness, the only things affected by it are creatures. This is an important point because if you brought say Chimeric Mass into you could not then pay 1 mana to make it a creature and attack with it, because it still has summoning sickness.
The only thing that creatures cannot do with summoning sickness is attack or use an activated ability that requires it to tap. Creatures with summoning sickness MAY still block. So say you cast Ambush Viper on your opponent's turn, it has summoning sickness but may then block whatever creature you wanted and in this case kill it, a very effective strategy.
In the case of Grand Architect you may tap whatever you want as soon as Grand architect comes in. The cost to play it's ability is tapping things, not necessarily Grand Architect. You may also tap grand architect however when it comes into play because of the distinction. Grand Architect is tapping an untapped blue creature rather than you tapping Grand architect. It is a fine line, but makes a world of difference.
First - Comp Rules 302.6:
302.6. A creature's activated ability with the tap symbol or the untap symbol in its activation cost can't be activated unless the creature has been under its controller's control continuously since his or her most recent turn began. A creature can't attack unless it has been under its controller's control continuously since his or her most recent turn began. This rule is informally called the "summoning sickness" rule.
tl;dr, it has to have been in your control since the before your most recent turn began, essentially.Note also that this concerns itself with control, not just existence on the battlefield, so if you do something like Mind Control an opponent's creature you can't attack it or use a tap ability yet.Second - Your wording's a little confusing, but yes, you can block with a creature that has summoning sickness. It just can't attack or use an ability with the tap symbol.Third - Again, correct. The mechanical, printed-text, cut-and-dry indicator is the tap symbol; if it has the tap symbol, you can't use it while it's go summoning sickness, but if it just says the word "tap," you can.It's a bit hard to flavorize this, but you can sort of see it as the tap symbol represents the creature having to put concentration and effort into the ability, while the word "tap" means it's being used by something else, so it takes less effort and though. I'unno.