I second the vote for the Astrale 8 - easy to install yourself (if you are a little bit "handy"), cheap ($40), and totally (so far) reliable. I find having cadence as the primary display and speed as the second display really helps me stay focussed on steady spinning and form.
Also, the link earler about changing a tire without levers is great - I followed and and changed a couple of tires for practice in the comfort of my living room, and then once I had to during a ride - thanks to the practice, it was very easy to do.
Congrats on the riding and weight loss, and welcome!
Keep calm and carry on...