Anyway I would like to do some renovations to the home now (cosmetics only.. exterior work mainly) and also start working on kitchen and bath cosmetic updates.

Anyone have suggestions for general contractors/electricians/plumbers and sliding/exterior work?

I specialize in exterior renovations, mostly roofing, siding, windows etc.

The HOA is responsible for the exterior of the building including the roof and drywall in case of the water leak for example.This is a rental property and I don't think I must have all coverages.

Always try to improve the exterior and make a good first impression of those driving by. 

You draw from the escrow account as you complete phases of work. (5K after exterior is complete, 5K after Rough Electrical and Plumbing, 5K after flooring, cabinets, etc. 10K at completion) This protects you and the lender from a contractor taking off with your cash and not even hammering a nail at the job site.

I purchased a lead test kit from Lowes to test for lead-based paint on the exterior of a property. 

Will re doing the  properties siding and some exterior upgrades be sufficient enough to force the appreciation or is the only way to increase the appreciation is to rehab  each unit?

The property I purchased had some intense exterior neglect in the landscaping, doors, and paint.

The property was built in 1984 and is in good condition interior and exterior.