Hey Steve,
Congratulations on your 149 purchase! I have 2 of them and they are very well rounded cubs with plenty of power, easy to work on, and plenty of power under the hood.
On this forum, the only stupid question is asking yourself whether or not you should ask your question. Overall, we are a friendly group that is more than happy to answer questions, help each other, and bring another member into our hobby.
To answer your questions, if the headlights were installed correctly, then yes they should have a fuse installed on them, that is typically close to the switch. However, those cubs shake rattle and roll a lot, so I wouldn't be surprised if the headlights need replaced.
You cannot run a mower deck AND a tiller together. Not for sure why you would want to anyway, but you cannot have both of them together. That is why a lot of us have multiple cub cadets, so we can have each one of them set up for particular duties. So, start planning for another cub cadet.....but they may be hard to find out your way is what I often hear.
Cub Cadet 123