I tried searching on line and even went through several rule books because I have been told that if a creature gives (1,1) counters to creatures of the same type does it also give it to itself. Such as Predatory Sliver which affect is "Sliver creatures you control get (+1,+1)" does it give it to itself
Yes. It is a sliver. Otherwise it would say "other" slivers.
Yes it does. Other cards will say "other goblin creatures you control get +1,+1" for example. Those do not self buff.
That's correct. And this should be in the rules section.
Always check the errata/rulings on older cards. Some are changed to say all, some to other, so it can depend. Newer cards are specific in their printings.