Unless you have training in spider identification, you will likely not be able to tell whether a spider is venomous or not. It is also dangerous to try to get close enough to a spider’s web to check its body for telling marks. Instead, let a professional investigate the spiders.
It is very difficult to get rid of termites, especially once you have a complete infestation. Whether you have termites for the first time or they have come back again, a pest control expert can get rid of them once and for all.