(1) and (2): Technically, seller will not have any problem forwarding it to the warehouse, it's more of the warehouse knowing what to do upon receiving the parcel on your behalf and whether will they forward it to your Malaysian home address.
Yes, you'll need your forwarder's permission and agreement to provide you their service. And you'll need to send your forwarder (Prouter/Dex) the link of the item for them to check if it's okay or to check for any special shipping requirement.
Different forwarder might have different ways of working things out, eg, different warehouse address, the format of shipping address have to indicate some special instruction and so on... I'm only familiar with Prouter and what I've told you so far are based on my experience with them. Do note that this is my first time arranging for an unofficial forwarding service with them.
(3) I'm not sure if you can see your 7 characters unique code if you have never use their official consolidator before. And I'm not sure how important is that 7 characters unique code if you're not using their official consolidate option. Check and see what's your forwarder's requirement.
(4) Nope, it won't appear in Taobao's system as this is arranged separately with your forwarder. The reason is, Taobao's has a list of item that they forbid for international shippping even though your local custom allows it (such item could be bulky items like furniture or stuff like handphones). So when that item that you're buying is on their own restricted list, there's no way of using their internal consolidate option to send your stuff to Malaysia.
So, the unofficial way can be quite troublesome and scary if it is your first time and you're unable to communicate efficiently in Mandarin. Hence we have agents out there who will help you deal with all these issues. I can give you a list of sentences that you can use to ask if they are able to offer forwarding services without going through Taobao, let me know.
For yeslogicstic, personally I haven't try it myself but my sister and her friends have been using it.
So far the stuff that I've bought are shipped into Malaysia thru Taobao's official consolidate option. The only time that my shipment was listed under sensitive item is because I bought a car 12v USB charger with bluetooth FM transmitter - the system will automatically put them for sensitive air shipping which is way more expensive.
I also had an experience where the international power adapter i bought got listed as sensitive item, I had to contact the forwarder to get it clarified. In the end, they changed it and place it under normal shippping.
This time I had to do it unofficially is because I'm buying a fish pond filtration system which is quite bulky.
by using Taobao's official consolidate option...does that mean they consolidate the items at the warehouse...and charge per kg (e.g: RMB 21/kg) shipment to msia ?
In that case...isn't cheaper to go with TGDS with 15kg as limit instead of RMB 21/kg x 15kg = RMB 315 ?