@MerakiMed easy one first - yes the MX68W does have two PoE+ ports.
Now for the tricky one....
The MX68W doesn't stop you adding an additional MR access point to the site (or Meraki Network in the Dashboard), but its not going to work as you expect. The MX wireless essentially uses a different control mechanism to the MR devices and so you lose a *lot* of capability around roaming, management of channel and power, and you will generally get an inconsistent experience between the two of them.
The MX68W is a great little box for a small office where you know you will only need one access point to provide a basic WiFi service, but if you are thinking you may potentially need two or more access points, then I'd be going MR. You may also want to stick to the MR if you are trying to build an organisation-wide consistent wireless solution, there is much an MR can do that MX wireless can't. I'd be thinking MX68 and use the PoE+ ports to power the MR access point(s).
On another point, don't look at the MR45, go with the MR46 - the price will likely be the same and you'll have a much more enjoyable experience. You may want to look at the new MR44 too, but I've no experience around that one yet.