Router speeds for different bits and types of wood

This is my first post after the intro and I have a few questions relating to general routing.

1. I have a Porter Cable 75812 router mounted on a Triton table top. I had to make my own fence as I bought this table top used with no fence, etc.. I also have a PC 6902 router, which I am selling now (fixed and plunge bases). With the 75812 router, can I use 1/4" bits or should I use only 1/2" bits?

2. Since the 75812 is a variable speed router, is there any resource available to find out what speeds I should run different bits at and what wood should be routed at what speeds? Being in Canada, it is quite expensive to find exotic wood and I am generally limited to curved pine lumber. Home Depot here only sells cedar, pine, oak and maple, unlike the many other varieties that I have seen being sold even in small towns in Wisconsin, USA.

3. I have been trying to make jewelry boxes using the pine bought from Home Depot and it always ends up being crooked, due to the curved nature of the wood. What wood should I use to make these boxes?

4. My router table does not have that round insert thing that sits around the bit, and it is very difficult to change the bits on this router unless you turn it from under the table and then bring it up. Is there a cheaper solution to this?

5. What methods do people use to accurately measure and adjust bit height?

6. What clamping techniques are available for cutting small pieces of wood on a mitre saw (holding it down with bare hands too close to the blade is dangerous)?

Thank you in advance


Judas