There are a few things wrong here and it is hard to explain but I will do my best:
Basically, DHCP is a process running on the router which "dishes out" IP addresses to any machine on the network requiring an address.
Now, Dynamic vs Static, Dynamic is the D in DHCP, in this context it simply means a client of a DHCP server. In this same context, Static simply means not using DHCP and manually configuring the network address.
When you set up a static address (default settings e.g. not setting an alternative), you are instructing your computer NOT to use DHCP.
Now, if you choose an address in the same range as DHCP, it is possible that the DHCP machine will try to give out that same address, in which case, there will be an IP Conflict on the network.
I would recommend that if you can not change the DHCP range, you simply add an exclusion/reservation on the addresses you want so they will not be reused.
Now for the second part, port forwarding does not matter, or have any difference in DHCP or Static, you simply give it the end address and it will forward to it.
Now lastly, re reading your question, if you are talking about your ISP giving you multiple IP addresses, this is a much harder and complex situation.
Basically put, a router uses a service called "NAT" which has a one to many system that can forward a port to an IP address connected to the same router. When you disable NAT, you are effectively giving every computer connected to the router their own direct line to the internet and there is no need to set up port forwarding as if a connection come in, it will go straight to them - your router is just directly routing the information.
This can get a lot more complicated and I am unsure to exactly what you need/what you intend to do. Please leave comments and I will be happy to help you further.