1. There's no such thing as a 30 years Home Return Permit (re validity).
Whoever mentioned it was mistaken. I've personally checked by asking when I first applied in HK. It's either a 3 years HRP for those under 18 years old (to be renewed every 3 years) OR, at the most, a 10 years one for those 18 or over.
2. The 'expedited' or 'express' service takes 5 working days (about a week if application submission is timed right; add an extra day for every public holiday during that period) and just costs HK$200 more. Usual service takes two weeks (if submission is timed right could be a bit sooner; again, add a day extra for every public holiday - especially just before BUSY festival holidays when you also have to anticipate queuing for hours!).
3. Opinion: Best to use relative's or friend's permanent address in HK - making sure it's written in Chinese characters. Also, on the form, put in the nationality box 'Chinese' and don't mention that you hold other 'foreign' passport(s) (they usually don't ask in the first place). Good luck.
Re SushiLover's query - I agree with User's response: just use up-to-date HKID and expired HRP card to renew HRP.
Can be as quick as a week if you pay an extra HK$200, as long as you (or along with a relative/friend) have filled in the form with info they ask for (at the counter), with the bits in Chinese language as required.
BTW, it doesn't matter how many years your HRP has expired by (so far as I know re adult permits, but I'm unsure about 'under 18s', never asked). The CTS 'entry permit' counter staff told us that once you've signed up for an HRP, it's 'for life' and they won't issue you with a China Visa (even via one's consulate, OR at least they shouldn't) because on their records you're already officially a 'Chinese National', (UNLESS you have formally 'renounced'...). So it seems that if you've acquired an HRP before their prerequisites/rules changed (circa 2005) to include your first holding an HKSAR passport, when you come to renew your HRP they should issue you a new HRP card without probs - no matter if you're a true 'Chinese National' or not, under HKSAR ImmD definitions (?).