which tuner ?

I always recommend VU+ boxes but i don't mean to be biased on that as there are many fantastic enigma2 boxes out there other than VU, it really is the old cliche tho on what you want to pay or can afford when you choose.

FBC tuners i am led to believe are fantastic so its your best option i would say with a single feed, however if your box does not have this tuner then you can only record one channel on one satellite at any one time but you can (restricted) record more if the channels are on the same transponder which are usually highlighted in your channel list, to add a second input it is just a case of a twin lnb and 2nd co-ax line to your receiver providing the receiver has twin input or more capabilities.

For iptv recording i have used an enigma2 app called Xtream which allowed me to record iptv but this app is usually sent as per your iptv provider.

Cant really answer much more except that timeshift and recording will work just fine on your enigma2 box with live satellite or cable channels providing your internal or external storage device is ok.

I got DM920,with triple tuner DVB-S2/T2/C2(Multistream-FBC-DVB-2X).

Only with unicable LNB can u watch one channel and record another channel.

There is special programm ,can u record IPTV,but is very complicate,I dint try it.

Transcode stream to computer or iphone;i dont know,and couldnt tell u.

Tuner is sensitive,but with size of your Dish and Sat equipment.

Yes u can use internal hdd for record or timeshift.

Audio PIP,Yes.

Yes,u can the box handle wifi for iptv,but must installe a USB wifi ,cuse DM 920 have not integrated wifi.