Email and Skype are shady platforms for discussing deals. They are best openly discussed here to give you and the buyer an opportunity to be transparent, fair and, most importantly, safe.
You must also know that a trusted escrow is strongly recommended for the safety of all parties involved.
As for e-transfers, be aware that they are reversible. The service provider, Acxsys, is known to reverse e-transfer transactions if there is any element of fraud involved, proven or otherwise. When the fraud defense is invoked, the sender usually succeeds in reversing the payment. Be very careful of this payment method. There were several Canadians on Localbitcoins who lost coins and money AND had their accounts frozen as a result of the reversal.
Wire would be a safer method for as long as you can conclusively and definitively identify the sender of the wire. Assuming you do have the 5 BTC, do not underestimate the importance of doing due diligence if you want to stop scammers from stealing them.
Use wire and do not instruct escrow to release coins until the money is credited to your bank account with finality. Never rely on screen shots or pics of receipts as a basis for releasing coins. Don't allow the buyer to pressure you to release the coins earlier even if evidence of payment is presented. Wait for the money to appear on your account. Do not take checks (cheques), money orders, drafts or anything similar. If you are offered a cash deposit to your account, double check and make sure it's cash and not a check.
As for the buyer, use a trusted escrow forum for a secure trade. Contact the escrow directly and wire money only after the escrow confirms the coins are in his control.
Just thought I would add, I like the way you lay out your warnings for both potential buyers and the seller. It's not often you see a well reasoned warning.