Toughness is calculated whenever State-Based Actions are checked, just before a player receives priority, and whenever else a spell ability asks for it.
704.2. State-based actions are checked throughout the game and are not controlled by any player.
704.3. Whenever a player would get priority (see rule 116, "Timing and Priority"), the game checks for any of the listed conditions for state-based actions ... This process also occurs during the cleanup step.
208.2a The card may have a characteristic-defining ability that sets its power and/or toughness according to some stated condition. (See rule 604.3.) Such an ability is worded "[This creature's] [power or toughness] is equal to ..." or "[This creature's] power and toughness are each equal to ..." This ability functions everywhere, even outside the game. If the ability needs to use a number that can't be determined, including inside a calculation, use 0 instead of that number.
Korozda Guildmage sacrifices creatures, and puts a number of 1/1 tokens into play based upon the creatures toughness. When the effect resolves, it cannot use the creatures current toughness, because the creature is no longer on the battlefield (and creatures do not exist anywhere except the battlefield, everywhere else they are creature spells or creature cards). So, it uses that objects Last Known Information.
608.2g If an effect requires information from the game (such as the number of creatures on the battlefield), the answer is determined only once, when the effect is applied. If the effect requires information from a specific object, including the source of the ability itself or a target that’s become illegal, the effect uses the current information of that object if it’s in the public zone it was expected to be in; if it’s no longer in that zone, or if the effect has moved it from a public zone to a hidden zone, the effect uses the object’s last known information.
So, for your individual questions, the toughness is calculated when the effect of Korozda Guildmage resolves. At this point, it uses the Last Known Information about the creature. This includes any effects that modify toughness (like Giant Growth that adds +3/+3 to the Power/Toughness, or counters that add/subtract from the P/T). Damage does not modify toughness, it is only marked on the creature to track lethal damage. So your answers are 7 (Giant Growth adds toughness), 4 (damage does not affect toughness), 5 (+1/+1 counters add toughness).
302.4c To determine a creature's power and toughness, start with the numbers printed in its lower right corner, then apply any applicable continuous effects. (See rule 613, "Interaction of Continuous Effects.")
613.3c Layer 7c: Effects that modify power and/or toughness (but don't set power and/or toughness to a specific number or value) are applied.
121.1a A +X/+Y counter on a creature or on a creature card in a zone other than the battlefield, where X and Y are numbers, adds X to that object's power and Y to that object's toughness. Similarly, -X/-Y counters subtract from power and toughness. See rule 613.3.
302.7. Damage dealt to a creature by a source with neither wither nor infect is marked on that creature (see rule 119.3).
