You should consider a water pump when you're in there, as well as valve cover gasket, cam and crank seals (I didn't bother, they looked good and they can be pita to replace. You can use a small flat head to do them but you have to be really careful.)
I also changed my Idler and tensioner These parts are relatively cheap especially when you consider the cost at a garage (I was quoted $1600)
Here's a link with every thing you you will need.
http://www.rockauto.com/catalog/raframecatalog.php?a=G-mazda
I would throw in a few extra items to help justify the shipping cost. (oil filters (I use the one for the 02 626, it's bigger and cheaper)air filters, head lights, plugs etc) Get the other belts too, about $20 AC and alternator.
Make sure your kit comes with a tensioner spring. If you're not sure just order one,..$2
The tensioner spring is important because the the tensioner pulley is "active". It pivots freely even when you lock down the tensioner.
I had a hard time with the cams. They wouldn't stay still when I wrenched them into place. They would spring back a tooth or so when I let go of the wrench. One guy mentioned to use two combination wrenches tied together to hold them still but I couldn't figure out what he meant. I hope you have someone to help you. 4 arms certainly make it easier.
I also left the spring off till the belt was on but it was too hard to attach it after it was on so I tied piece of wire to the end of the spring so I could pull it up and hook it on the pin. The end at the tensioner has to be attached before you install it.
I also realized that the timing marks are also on the other side of the cams and it's way easier to see them when you look at them from the driver's side.
Make absolutely sure all three marks line up. Rotate everything a bunch of times till you're certain.
I had my belt on and off 8 times before I was satisfied. I had to use my elbows to hold everything while I put the belt on. That part took me 4 or 5 hours, but I finally got it.
Make sure you use the right timing mark for the crank shaft it's the one underneath the crank pulley, a little notch.