Two out of three of the proposals make good sense.  The US exists in a competitive world, and our tax system needs to take that into account.

Multinational corporations, whether the parent company is based in the US or abroad, make decisions all the time about where to put the next manufacturing plant, research center or headquarters.  The US's current corporate tax rate of 35% puts the US economy at a serious disadvantage when almost all our trading partners have rates of 15% to 20%.  Get the jobs and wealth here!  Lower the corporate rate substantially  --- whether 15% or 20%.  Find sensible ways to raise revenues with other taxes, such as energy or financial transaction taxes, VAT, border adjustment taxes, changes to individual rates.

Profits held overseas produce no tax revenue.  Charge a much lower rate and bring the money home.  This will produce substantial one-time tax revenues and bring more wealth into the US.

Full expensing of capital investments makes no sense.