I rather go with W750BT big screem around RM 838 ~ RM 899 and buy a universal WiFi Mirrorlink Wireless device that goes around RM 210 ~ RM 250. Because I did research that XAV-712BT mirrorlink system mostly works on android phones and requires USB cable connection in which is frustrating for some. So why not do it wireless? Since 2015 phones on wards have the wireless display capability so as iphones have AirPlay.

Currently I'm using Sony W650BT not 750BT cause wrong typo. Price is RM 699.50 plus shipping. Original from Sony Malaysia, i bought it from Lazada. Worth it.

Talking about Waze, you need to add WiFi mirrorlink mirrorcast device as an add-on if use Sony.

The front and rear sensors is stand alone, nothing to do with HU.

Reverse camera can be retain for sure.

The GPS unit is built inside the HU, when replace the HU, it goes with it

The best you can do is try opening your HU back unit to find whether does it have "AUX IN + Video IN" if YES, then you don't have to replace HU. Just buy china WiFi MirrorLink MiraCast device below rm 300 and install inside. Then you can use WAZE because 2015 android phone onwards support "WIFI Display"/

If is proprietary connectors then you're out of luck, unless someone who can get you some info about the HU. Since your reverse sensor and camera are connected to your HU, Sony doesn't have that.

So far no GPS in Sony. I've seen Kenwood and Pioneer has that, but is in the range above RM 2k... I wouldn't spend so much for my HU for having GPS. I rather have my GPS on my phone, such as WAZE

If you want to have better sound in your car, can buy a 4 channel amp with Speaker input such as JVC KS-AX3204 in which is the most affordable amplifier you can find in Lazada. I bought mine for RM 349. Original from JVC Malaysia.