New to welding and a couple issues so far

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Hey all, so I bought a Lincoln AC225 Arc Welder a couple weeks and have been practicing on scrap metal so far.  I've practiced with the following electrodes (all 1/8): 6011, 6013, 7014, and 7018AC.  Mostly I practice running beads and occasionally will tack up a joint to practice, usually flat position fillet on T-joints.   One confusing thing is this porosity I'm getting on some of my 7018AC beads.  It is Lincoln brand rod that I got at home depot, and haven't stored in an oven or anything as I'm only practicing with it.  Here is a picture of what is happening: This one has multiple holes but usually it is just 1 or 2.  This was run in the flat position I believe at 135A, but I know it also happens at 120A, although possibly less so.  I tried grinding down a couple of the beads and the hole goes a little ways down but seems to stop before getting into the base metal.  This definitely isn't happening with any of the other electrodes.  The slag on these beads does come off nice and easy, but often leaves a couple of these holes.  Here is another picture of a horizontal position fillet weld I did with 6013:I'm happy to be seeing some of my first semi-smooth welds, although this one seems to have some pretty bad undercut on the upper piece.  I'm pretty sure I did this at 105A, which doesn't seem like it would be too hot, but possibly?  I was also thinking it could be related to rod angle.  I do remember the slag being hard to get off on this one.  Is there anything else you can tell just by looking at the picture?Thanks.
Reply:E 7018  alternating current rods are troublesome from my experience.  If you are not careful when striking up and keep a tight arc you will get porosity when you start.  You seem to have porosity all along...Maybe increase you amperage and hold a closer arc.?  It definitely is not too hot.  When you run 7018 at too high an amperage you get spatter ... more like globules of metal sitting on each side of the bead.  Your horizontal fillet with 6013 is good except for the undercut on the top edge.  This is typical for a novice.  Likely you are moving your rod up the vertical face a little too much gouging out the parent metal.  The fillet looks like a good 45 degrees so you must have been holding your rod at the right angle... just moving up the vertical once and awhile.
Reply:first off get a DC welder it is much easily to weld with
Reply:On that horizonal weld you need to cool it off 10 and win you step make a circle and hold just a second on the top and you can probably get rid of that under cut