Hi
Take the medical before you start that way you're not committed to any high expenditure or wasted lessons if you should fail. The medical lasts for 2 years and you will have to have an ECG if/when you are over 40.
Can't see any reason to do your training on a 44 unless you really want to and the money is not an issue. If you want the 44 rating, do it afterwards that way you will have both on your ticket as they are classed as separate types.
I guess there would be no harm in starting the gound school but i'm not sure if you have to have the complete course finished within a specified time period. A flying school will confirm that particular one for you.
Your license will last for 5 years but you will be require to complete an LPC (License Proficiency Check) each year (for each type) to keep your ratings valid. After the 5 years you will need to renew the license - which is basically a paperwork excercise.
Why don't you pop into your local flying school and review the options with them. Just don't part with huge sums of cash in advance regardless of the discounts that may be on offer. Pay as you go!
Joel