There are these things like p_i1635_3_ and func_145748_c_ and things like that in minecraft forge 1.7.10. What are they and how do I know what to enter in place of their value?
Those are SRG names. They're halfway in between the truly obfuscated names that Minecraft shipped with, and the MCP names that are completely human readable. The conversion of SRG to MCP names was a long ongoing process, and it wasn't completely finished in 1.7.10 (and never will be since it's over 7 years old now). To figure out what they are, either look at the context it appears in, or look at the equivalent code in a newer version of Minecraft.