No disrespect intended, my friend, but don't you have a POH for the airplane handy? It would have recommended speeds for the maneuvers. Of course, you can use Va or less.
I remember that in the Arrow I flew years ago that although my instructor said otherwise the POH said you were not supposed to set 25-square for climb power. You were supposed to set 23-25 for climb power. 23-23 is a good rule-of-thumb cruise setting. You can try 15-18 inches for descent power. Of course, you don't want to go below the bottom of the green arc on the MP gauge.
To set up for flight at critically slow airspeed (MCA), I reduced power to 15 inches, and during the first clearing turn at flap range I put out the first notch of flaps, during the second the gear, and coming out the turn the rest of the flaps, moved the prop lever full forward, and added enough power to maintain just above the horn. Of course you're maintaining altitude and heading per the appropriate PTS standards.
For stall recoveries, recover as with any other airplane. Release back pressure enough to break the stall, full power, pitch 5 degrees (whatever puts the cowl on the horizon) and flaps 10, raise the gear, positive climb, and raise up the rest of the flaps slowly with the Johnson bar. Of course, you are holding heading +/- 10 degrees or whatever the PTS says. Same basic procedure for go arounds. Lead with pitch up, full power, flaps, gear, flaps. When I think about it, it really is very much the same as with a Seminole.
I remember that it was easy to flood the engine during startup if you weren't quick enough shutting down the electric fuel pump during priming.
The airplane is really basically the same as the other Cherokee derivatives that I'm sure you've flown, after I viewed your profile. Maybe a little easier to land because it's heavier than a Cadet (Warrior) or Archer. I always thought Piper was easier to land in a crosswind than Cessna.
Hope this helps a little. The Arrow is a nice instrument platform, by the way.
Of all the planes I have flown the Arrow has worked out to be the best. It is the most forgiving and allows you to use the POH to the best. First thing to remember is that the POH is set on a brand new Arrow with no time on the engine. Also here comes all the standard BS of 15C and @#$%. My best recommendation is to work with the plane to meet the PTS. The POH is close but in the end you as the PIC will be able to find the correct manifold settings.
Have fun with the Arrow. It is like a lady treat her nice and she will give you the pleasure of your life!!
The old Arrow III's fly just like any other Cherokee with a slightly heavier feel due to the landing gear stuff adding weight. Read the book and any STC notices about your landing gear system - Piper added a free-fall "auto-extender" to the later models of the original Arrow. When you reduce power (i.e. pull back on throttle) to a certain level, the gear will fall out. There is an override button behind the flap handle, to keep the gear up if you want to do manuevers. ON SOME Aircraft, this has been disabled! Read all the materials and never assume you have landing gear in the arrow until you see 3 green!
Arrow IV's with T-tails have a nasty trick unlike any other Cherokee. The T-tail looks neat, but it also removed the tail from the prop wash. The normal (straight tail) Arrow lands like every other Cherokee in that for a really smooth landing you just keep pulling back on yoke and lifting the nose and she'll settle right in. Do that in a T-tail and the tail (now out of prop wash) will stall and the nose will fall rapidly to the pavement. Always carry a little extra speed in a T-tail to account for that tail stall.
All injected Arrows are tough to start when hot. (Fuel spider or distributor is mounted on top of the engine!) My technique is to crank the engine and then push the electric fuel primer, this "purges" the lines of vapor and usually gets a good hot start.
The Turbo-charged Arrows are an animal all unto themselves. Cantankerous to start. Extremely sensitive to hot and cold. Very prone to failure as the Rajay Turbo runs completely too hot for such a small engine. Fun to fly at almost 180 knots but man do you have to pay for that speed! Find somebody who owns one to learn all the idiosyncracies. Also, don't use this airplane for stalls and slow flight - you might as well just head straight for the maintenance shop to have a top overhaul after supercooling the engine doing those manuevers.