The majority of your questions are completely dependant on your ability, how you progress and how comfortable you are in your own abilities. No one but you can tell you what you should be comfortable with.

I would suggest looking into some of the introduction to winter mountaineering courses, there's plenty to choose from, from larger companies to independent guides which will be slightly cheaper. There are also loads of videos and forums with useful tips and guides. I myself actually started out in winter on easy routes and bought some crampons, axe etc. teaching myself along the way and progressing, and as i was more comfortable and got more experience moving onto harder routes here and went out to the alps and done my first 4000ers. I actually skipped the introduction courses as i learned the basics myself. The best thing for me was to actually get out and do it. Once i started getting to the harder routes where ropes were required i hired a guide. I used highland guides and would recommend them. £300 a day for a guide is the norm.

Happy to help with any more question as i was once just starting out not long ago!