1) Taking kugel out of fridge on shabbos morning, and putting it on a hot plate on top of a upside down foil container: is this a problem?
2) Can one use ky cream on shabbos (a lubricant cream)?
1) It is permitted to place the food on top of a foil container.
Sources: There are different types of hot plates, some that are suitable for cooking on, such as a blech (tin sheet that covers the flames), and some that are not (standard electric hot plates). Concerning an electric hotplate, Harav Moshe Feinstein (Iggros Moshe, vol. 4, no. 74, sec. 35) permits placing food directly on the plate, because this is not considered an ordinary method of cooking (based on Shulchan Aruch, OC 253:5). Most authorities do not mention this leniency (see also Shemiras Shabbos Kehinchasa 1:25), and many do not rely on the heiter, but I heard from Harav Scheinberg shlita that one may rely on it.
Concerning the more stringent type of hotplate, meaning a plate that is suitable for cooking, or a blech (a tin sheet that covers the fire, which is considered like a covered fire according to most opinions), it is permitted to place food on top of an upside pot, even when the pot is empty.
Although Shulchan Aruch (OC 253:3) does not imply this to be the case, according to Chazon Ish (OC 37:9) placing the food on top of an upside down container is considered semichah (placing food close, but not on top of) a fire, which is permitted according to many poskim. According to Shulchan Aruch Harav (Kuntress Acharon 10), it is permitted because it is not considered an ordinary method of cooking, and therefore there is no prohibition with regard to a kugel, which is already fully cooked. This is also ruled by Tehilla Le-David (253:18), based on Magen Avraham. It is also the common custom in many households.
2) It is permitted to use KY gel on Shabbos; the possible prohibitions involved in regular cream (memachek) does not apply to this type of gel.