Depends on what it's about too and how close the friend is to me....
If it's just a "hi-bye" friend, and when suddenly contact me and try to reminisce the past, I usually won't be so nice to them. Cuz if they never were serious about friendship to let it disappear by not keeping in contact, why bother now? Cuz they need help to meet a sales target or a particular purpose?
If we lost contact cuz it's my fault (e.g. I move out, lost number) and this friend managed to contact me... I'll be nicer la... But again, my principle is I never mix work with personal matters... I'm super-strict with work matters (e.g. insurance, MLM), so a friend wants to work with me, they better keep to my work expectations... If not, I'll treat them just like any insurance/MLM agent...
Anyway, to TS' post...
1) I'll listen, but they will find it harder to convince me... If they manage to convince me, they better be prepared to work double-y or triple-y hard to get me a good return plus excellent coverage...
2) Again, I'll listen out of courtesy... But I will not commit...
3) Courtesy, I'll go... But it'll definitely affect the size of the angpow I'll give...
4) Out of courtesy again, will listen... But bear in mind that once she's cried and vented anger enough, she'll still go smooching back to her Loser-of-a-Boyfriend, so whatever happens, do not commit in this case... Keep an open mind, do whatever you feel comfortable doing for a "normal friend +1", nothing more, nothing less... Comfort her, offer a shoulder... Get free hugs in return (it's a fair exchange anyway, you give comfort & a listening ear, she has to give something in return, no?)
Again, same rule applies in all 4 cases...
If they were never serious about the friendship to let it disappear by not keeping in contact, why bother to try to salvage what's left now? Cuz they need help to meet a sales target or to fulfill a particular purpose?