As for the towns themselves, they are the place where you can buy and sell goods, upgrade/enchant equipment, gain new classes, and generally have fun. All NPC's are randomly generate and very much open to any form of proposed sex with anyone. Shop NPC's will even give discounts if given an above average experience (so use of monster abilities is encouraged).
Also gained through sex with NPC's are quests and buddies. Quests will have an objective to complete with a reward (loot and sex) upon completion. Quest NPC's from different towns will reappear in other towns if the quest is completed, but will vanish after you “obtain your reward”.
As for buddies, once you get high enough level (20), you will be able to gain NPC friends you can form a party with. You will be able to gain up to 5 NPC buddies, and you can summon them to any portal you enter. To gain an NPC buddy, simply have sex with said NPC and at the end you will be given the option to make them a buddy. They will have their own class and starting gear, but you can change this if you want. If you ever want to get rid of a buddy, simply uninvite them from your list and they will be gone.
Last, but not least, many medium to large size towns will have flesh-tailors. These NPC's will be able to reshape your looks if you find you are unhappy with your original transformation. These NPC's come at different levels with some only able to change hair and eye color, and others so advanced that they can change size, sex, and race (you can alter buddies with this as well). Town portals are very stable, usually stay in the same spot for weeks to months.
The other shopping friendly portal is the merchant portal. Unlike the town portal, the merchant portal is only sellers, shops, caravans, and markets. These portals range from bronze, to silver, to gold, and maybe to the fabled platinum and jewel encrusted. Merchant portals sell rare goods and offer special quests.