You don't debut young fast bowlers in the sub continent. Just shouldn't do it.
I'd agree if we're talking a genuine quick like Pattinson. A nice easy introduction against NZ or WI would be perfect either home or away if you can. Copeland is a very different kind of bowler though.
Johnson can do well on those types of pitches, it would be good to have a hit the deck bowler on a dry pitch. Copeland's lack of pace would be bad and I trust Harris to do a good job. So I'd drop Copeland.
Complete disagree obviously. Johnson can do well on any type of pitch. Point is he usually doesn't. He just doesn't have any control and if it isn't doing anything off the pitch or in the air he's just going to give good batsmen too many 4 balls. He also doesn't really hit the pitch. With his low arm he skids it and that just makes anything with width bounce 20m back from the point boundary fence.
Copeland's lack of pace is more an asset than a liability. Combined with his height and control he just doesn't give you anything to drive, cut or pull. You have to go unorthodox to try and make something happen either by backing away or by going across your stumps, but that opens up the chance for him to attack the stumps and get you bowled or lb. Much harder to time, and because he's coming down from a much greater height he gets more variable bounce on flat decks than Johnson. If a crack opens up just outside off and just short of a length Copes will hit it all day long, Johnson wouldn't get within a metre of it. And lastly you can bowl Copeland all day long and he'll back up again tomorrow. You wouldn't trust Johnson for any sort of long spell in adverse conditions even if he's having one of his rare good days. Can you imagine the carnage if he loses the radar completely and the spinners are getting stick? You're left with bowling Harris and Watson into the ground and breaking Harris and leaving Watson too stuffed to open.
Harris doing a good job is a given, but not for 25-30 overs a day on a flat deck at high temps and 100% humidity. He needs to be used sparingly in short bursts same as Johnson, but unlike Mitch you don't need to cross you fingers and hope that today will be one of the days he can hit the pitch. He won't survive the three tests if he has to bowl a huge amount of overs, but use him smartly he'll make the breakthroughs you need. Watson similar in that you can't bowl him too long, but he'll come on and wobble it around and get you a wicket.
That's why I see Copes as a must have. He will do the donkey work for you, but still pick up some wickets and has the ability to run through a side if the conditions are favourable. Siddle will be called on to do this job if he's picked instead, and will probably do it ok, but he's a more hit and miss proposition than Copeland I believe.