Ok we'll talk about the shifter first, when replacing things we all know there are other things related to the part in question, in this case there is a rubber seal that bolts to the floor and the shifter sticks up through a hole, this gets brittle and torn, I would plan on replacing it because when you install an aftermarket shifter you need to trim the hole to fit tight around the shifter tower, it needs to be pliable (soft/streachy) so it seals around the tower to keep out road dust and hot air.
Now about those cats, you need to keep them in the box, you don't want them to get loose and be running about the neighborhood terrorizing the other critters and you'll know where they are at when you need a 'cat scan'.
But when you're ready to install them take the car to a reputable muffler shop because they need to be welded in place, you will not be able to hand someone the pipes and cats off the car, I guarantee they will not fit.
Water pump, this is subjective, If you do nothing, not replace the seeping hose and just kind of forget about it it will likely last a long, long time, if you go to all the trouble to replace the hoses and not the pump, well you can guess what will happen, the water pump will start seeping out that weep hole you read about in about a week, you won't even have to drive it, it will just happen as if by magic so if you replace the hoses I would do the pump too. JMO.
Gaskets, another subjective subject so let go to the old say'n ' if it ain't broke don't fix it ' but I would do the valve covers, this will require removing the upper plenum so get a gasket for that at the minimum, unless it has been removed before, this will also give you a chance to inspect things like the pvc grommet, screen and hose(you may have replaced these items before) and look for signs of seepage at the back of the intake along the wall at the back of the engine.
REMEMBER, things can snowball into ' well since I'm here I'll just fix this too'.
First time clutch job can be done by one person but I would suggest bribing your friend to help, he seems to have a sense of humor.