MDB

Assuming there are no issues with the paperwork, you are waiting for "Case Complete" (CC) from NVC. This typically takes ~2-3 months or so.
http://www.visajourney.com/content/ir1cr1historical
NVC wiki: http://www.visajourney.com/wiki/index.php/NVC_Process
 
Once you reach CC, they will schedule the interview. I'll defer to other members for the specifics with Australia in terms of how long that takes and the notification method (I would presume email but some embassies/consulates do snail mail still), and the medical aspects.
 
Happy birthday!

Based on the story you told, if he's visited a few times for more than a couple weeks, you should have no problem.  That age gap is not unusual for expats living in the Philippines with Filipinas but it IS on the high end, for visa cases.  Still, the key will be how much time you've spent together in person.
 
If he can be there for the interview, that would help.

Abi, 
 
most similar cases here ended very bad for the USC. We had women here who have been put in really bad situations after the foreigner got his GC and they only found out later that love is blind. They were made to believe that they press for the "process". Everyone could manipulate a partner to believe so. A 22 year old little boy, with a 62 year old women, just is not common. In fact, in places without immigration benefit, such relationships to end in marriage is 1 in a million. However, when immigration is involved from a 3. world country, such cases are VERY VERY COMMON. Thus, there is something else in play rather than love. Again - love makes blind. Take care of yourself and don't be tricked into believing something easily.  As for USCIS, of course you can file and try your luck, but they are well aware of such cases. In fact, all over the world, older well situated man mingle up with younger women and marry. This type of age difference and marriage is seen also without immigration benefit. However, a 22 year old boy to marry a 62 year old women, happens close to never anywhere in the world.