Where is the anchor locker in relation to that horn cleat. A vertical windlass usually has a chain pipe near it as part of the installation, and the chain pipe obviously needs to be over the anchor locker, provided the anchor locker is deep enough to allow the rode to fall into the locker properly.
A mooring bitt is a good idea, provided you can support the base and anchor it to the boat's structure properly. Mooring bitts, due to their height, allow the rode more leverage against the deck and should only be installed if they can be tied very securely into the deck and preferably the hull.
The last one I installed had a stainless steel bracket as a backing plate under the deck and the bracket tied the mooring bitt to both the deck and an adjacent structural bulkhead. You might be able to do that, since the chainplate for the inner forestay is probably fairly heavily secured.
If you can't do this, I would recommend installing TWO horn cleats. This way you will be able to accomodate the anchor rode and a bridle, which is a necessity if you have an all-chain rode.
I would recommend installing a chain pawl, since it will make hauling the anchor rode back up if the windlass fails much easier.
As for the bow roller, where you install it is going to affect where and how you mount the windlass. I'd point out that you will probably want to use a bridle to keep the loads off the bow roller, many of which are not robustly enough designed or mounted to handle the loads that anchor rodes can be subjected to, especially in storm conditions. You can also move the rode to a chock, but that is generally not as useful as having a long bridle, since you would have more problems if you have to let out additional scope.
BTW, I recommend having a relatively long anchor bridle, since a short bridle requires that you retrieve the anchor rode a bit to disconnect the bridle before you can let out more scope. A bridle should be at least 50' long IMHO. If you anchor in 15' of water... you can let use 10' or so of bridle, but it will allow you to let out an additional TWO scope, so you could go from 6:1 to 8:1, without having to retrieve the rode or move the bridle's chain hook. I'd point out that in good conditions, 5:1 or 6:1 is pretty typical, and that there is little effect of letting out additional rode once you get to 8:1 scope.
I have a couple more questions about deck layout for anchoring. Below is a picture of the bow of my boat. I just ordered a vertical windlass for it. At this point I think I'll have to remove that big horn cleat because it will be where the windlass needs to go. However I think I'll still need a horn cleat (or cleats) somewhere to tie off the anchor line and In any case I'll need one for docking. Where should that cleat go? I'm assuming it needs to be somewhat in line with the bow roller so I don't put any later force though the roller. Secondly is a horn cleat the best thing to use? I've seen a few boats with mooring bits. Are they any better? Finally when at anchor does the rode typically still go though the bow roller or is it moved to a chock? Thanks.