Hi @NagulMeera,
I’m sorry to say that Unified bootloader shared on the community is only unofficial demo provided AS IS with no guarantees and no support. Currently we do not have resources to support this demo. I will try to answer your questions through their documentation, but if follow-ups appear, please contact their support page instead.
Q1. The Unified Bootloader Demo projects were published quite some time ago. It uses S32DS for ARM 2018.R1 and SDK 2.0.0. If you need to port it to S32DS v3.4, you will need to do it manually, or try the "migrate" option, as shown in this video: Video: Migrating S32K1 projects from S32DS for ARM and SDK 3.0.x to S32DS 3.4 and SDK 4.0.2.
Keep in mind that this is for the SDK SW, if you are using RTD, this option may not work as expected.
Q2. & Q3. Have you read the Unified Bootloader – User Guide & their UDS Bootloader Implementation Guide? I can see from them that 0x34, 0x36 & 0x37 services are implemented:

Also, UBLUG mentions the following: "TP: For current version, TP include CAN and LIN. CAN TP is based on ISO15765-2 and LIN TP is based on ISO17987-2." ISO15765-2 being ISO-TP.
Q4. & Q5. For CAN-based firmware updates, you can refer to this application note: AN12323: S32K1xx Firmware updates – Application Note. Specifically, SCENARIO (1) shows the steps on how to handle a firmware update by receiving the new FW via CANFD.
Best regards,
Julián