Started my first business in 1974, been going strong since. My business portfolio is varied. Recent focus has been setting up 10,000+ reqs/sec WordPress sites. Most hosting companies can barely make 10 reqs/sec. Anyone expert who tells you "WordPress is slow"... Do a 180 + run, as likely their incompetence is pervasive. For example, SERP Shaker WordPress sites I've been setting up recently clock in at 7,000+ reqs/sec. In November + December 2014, one of my clients ran sustained traffic, all day, every day of 100,000+ unique visitors/second on a $100/month dedicated server machine at a load of 5%-10% of capacity. If you site is slow remember, site speed depends primarily on the tuning of the server machine where your site is running.
If this is your first time doing this, likely best for to first hire a full time or Fractional CTO to hire this team.
There are just to many variables to consider.
The primary variable is the code you're producing + how to ensure quality.
A CTO, with decades of experience + well versed in all manner of technologies, is essential to ensure you're correctly allocating developer funds.
If you miss this step, likely you'll either overpay or underpay, almost surely having problems delivering product + ensuring delivered product quality.
Fiverr. Guru. Any microwork site.
And... If your site is a money site (paying your bills), stick with WordPress.
Custom code is far more expensive to design + maintain + always far more hackable.
Also WordPress sites run much faster than custom code sites, because with WordPress caching is already thought out + implemented well.
With WordPress, sites can easily be built to maintain a 1,000,000+ requests/second on cheap hardware.
Attaining this performance level is possible + generally costs a large amount of budget to implement + keep working.
You'll use WordPress if cost + performance are a consideration.
You'll use custom code if you're independently wealthy, with unlimited time/budget... also patience... as custom code will leave you balled up in a fetal position, sobbing yourself to sleep many nights.
No need for a "Pro".
Just call the IRS + ask for an EIN to be assigned.
If your business entity qualifies for an EIN, the IRS will assign you one.
If you do hire a Pro, the cost for their service should be $0, or billing for the number of minutes they're on the phone with the IRS to freely assign an EIN.