Well, the most senior and respected as well as very much reliable member, pshamim sb, an ex-PAF pilot, himself had revealed that H-4 was in reality an A2A BVR missile with 120 KM range, based on rather ToT version of R-darter missile, ToT given by South African company, the package included other PGM techs also in it and China was a partner to this deal, meaning it got the tech also since it was under sanctions during that era, so it was the silent partner. H-2 was the 60KM PGM and just by adding the rocket booster, the range can go to 120KM, which doesn't needs to be given any new name to it.
So, H-2 & H-4 were two separate programs, one a PGM and another A2A missile program.
For further info, you can check the H-2 & H-4 thread, in which pshamim sb has posted the Crescent Arrow (Pak version of R-Darter) missile, taken by himself, and the original R-Darter missile.
And as for Mica missile, it was or is being considered or PAF rumored to be showing interest due to the RC-400, meaning a package deal. We may not have shown our interest, but most probably the seller may have said to give the radar, if we have a package deal which involves weapons also, as it gives boost to their sales. So, out of necessity, PAF may have been evaluating the Mica missile. Not out of its own option.
Also, since South Africa gave the missile tech to China also, its very likely that the same or improved seeker tech or other missile tech has been used in the newer variants of SD-10 also, as we did heard little from Chinese news sources that the latest variant has some new seeker, not based on the Russian tech as previous missiles had.
And one of the other reason for going with SD-10 would be, to give it more chances of commercial success, as PAF using SD-10 with JF-17s, will give it a good boost to score any export success. So the SD-10 sale to PAF may be for commercial purposes, rather then for actual war purposes, or may be PAF is looking for diversification, in case one BVR gets easily neutralized during war time.
And the reason for getting Pak made BVR missile was to have a stop gap measure for the time till more capable missiles come into service, so who knows may be with Mirages going out of service, the Pak made BVR missile also goes out of service as they may have served their purpose.
Pak made BVR missile gives Pakistan a great advantage and that would be the tech which it will be using will be known to itself and less chances of someone else knowing about it and leakage of info and then the neutralizing of it by the enemy. As pshamim sb did said that we made in house modifications to the seeker technology to make it more deadly and effective as it was already based on Israeli tech, so they might have known about the real product.
Here, read what pshamim sb has to say:
http://www.defence.pk/forums/wmd-missiles/28713-h2-h4-aam-agm.html#post409117
http://www.defence.pk/forums/wmd-missiles/28713-h2-h4-aam-agm.html#post409139
http://www.defence.pk/forums/wmd-missiles/28713-h2-h4-aam-agm.html#post409169
http://www.defence.pk/forums/wmd-missiles/28713-h2-h4-aam-agm-2.html#post409647
http://www.defence.pk/forums/wmd-missiles/28713-h2-h4-aam-agm-2.html#post409757
Chinese transfer of tech being talked about:
http://www.defence.pk/forums/wmd-missiles/28713-h2-h4-aam-agm-5.html#post413286
Plus you can read the whole thread and get the idea and what pshamim sb had to say in the other posts.