Johnnie Jackson explains that he substituted Ryan Inniss at Portsmouth because he was starting to have a hamstring problem. He also praises Scott Fraser: https://londonnewsonline.co.uk/charlton-athletic-boss-on-why-he-subbed-off-ryan-inniss-in-2-1-win-at-portsmouth/
As far as Mason Burstow is concerned, those fans cancelling their Valley Gold subscriptions should remember that we poached him off Maidstone United. He wasn't an Academy product.
We are a third division club and even when we weren't we were a selling club. Remember Scott Parker? Those are the financial and player career realities in football.
There is no reliable information on the fee, but my guess would be £2m - £3m plus add ons.