You said you are putting 5% into your 401K & additional ?% into a separate account...that is good. But my advice is to go higher (in total 401K+Roth+PlayFund...I can understand the concern with your employer). For many years, I was only putting 6% of my income into a retirement account (for me...
Find a brokerage with low fees (both transaction & maintenance). Lately many have gone to no-fee transactions. If you are going to play the market then you need to think of this money as gambling money.
Separately you need to have a separate pot of money you are putting away for retirement...