Realistically, as to the "need" for a forward assist and/or the dust cover, no and no for your intended purposes. For me, even though my intended uses mirror yours, yes and yes, but only mostly because any AR-15 rifle just doesn't look right to me without them (a patently indefensible reason in terms of an objective point of view
) and partially because these two features do offer some potential merit in extreme circumstances; they don't add that much weight to the rifle and they really don't cost that much more than one without them.
The biggest advantage to a chromed barrel imo is that they can be easier to clean.