Aaaarg Cupcakes how bloody annoying for you. Temping may be useful - it's worth giving it a shot to see how you get on.
I use Fertility Friend - the basic charting function is free, but if you want the extra bits which allow for extra obsession information, you need to pay (it's about £30 for a year although you can get shorter subscriptions).
The thermometer just needs to go to 2 decimal places - you can get farenheit or celsius - FF works with both. You can get them on Amazon or Ebay - just search for "fanjometer" "basal body thermometer".
Re: timing, it's best to take your temp at the same time every day when you've been asleep for 3 hours or more. I take mine at 6:30am every morning (I set my alarm at weekends and when I'm on holiday and then go back to sleep!). There probably isn't much point taking your temp if there's a huge time difference - just leave it out that day - you will be able to see a much clearer overall pattern.
Re: how to take your temp, it's a matter of personal choice! I temp fanjoly because I get much more accurate readings that way - the first couple of cycles I temped orally but my temps were all over the place that way - it depends on whether you sleep with your mouth open, drink water during the night etc etc. Up to you though!
I really enjoy temping - I did think that it would make me really obsessed, but actually it makes me more relaxed about things - I know when I ovulated, I know if AF is coming because my temps drop - when she does appear I've already got over it and moved onto the next cycle.