Congrats on ur new ride.
Parts you can source from sharjah from gulf star. Cheapest than all and about 50% discounted price than Al Tayer.
If you need to put lot of pressure on braking, that doesnt sound quite right. Its one of the weakest part of disoc and MOST expensive to repair. I am 90% sure its not pad its not rotor. Its the master cylinder or caliper piston is weak. Both are expensive.
You might not find any trustworthy garage, so its better to do check on 3 people and get the job done from one who sounds educated and talk logic. I havent find one trusted garage in 7 years. As first time every garage wants to be good with you to make u regular and after 1st or 2nd visit they rip u off completely.
engine oil, Shell helix is good and valvoline is good. Never heard of diesel oil in disco. Is ur discovery diesel engine?