Som bits and pieces about the garrisons:
Koporie seems to have had a very small garrison (12 soldiers) when the Russians entered Ingria, but the fortress was apparently abandoned almost immediately - Rullor 1620-1723, , SE/KrA/0022/1700/20 (1700), bildid: A0054479_00344
Nyen: Two companies of Horn's regiment in Narva were stationed there - Rullor 1620-1723, , SE/KrA/0022/1700/20 (1700), bildid: A0054479_00317
Nöteborg: The garrison seems to have consisted of about one company and a compliment of "soldiers' sons". In 1702, before the siege started, the garrison consisted of slightly more than 200 men.
When Otto Vellingk took over as Governor in 1699 he wrote that three companies of Tiesenhausen's Cavalry regiment were stationed in Ingria (Vellingk to Charles XII, 12 August 1699, Livonica II, vol. 192)
When the news from Riga arrived Vellingk began raising more troops. On 31 March he reported that he was intent on rasing a regiment of dragoons in Kexholm County. He wanted, he wrote on 21 April, to make it a permanent regiment.
Vellingk also wanted to raise a regiment of infantry (also permanent). He wanted to begin by using two existing companies from Skytte's regiment, one stationed in Kexholm and the other in Nöteborg. This the King rejected, but the regiments were created (1,000 infantry, 600 dragoons),