uhm.. to edgeguard like all of your smashes will work if you learn to use them. especially f-smash. if you want a kill, your f-smash and your upsmash are really your best options. as for the range you kinda get used to it the more you play... I'm usually playing in my opponents face anyways. you can also tech chase with a running usmash if that helps...
upsmash->down B will help you kill a little faster too sometimes, and even if it doesn't kill them, hurting them a little more is better than doing nothing.
Don't be too scared to use electric attacks even though they hurt you, they are often pretty useful (you shouldn't be doing more than 25% to your self per stock max. though) Jolts are pretty good, F-throw can be good, fsmash is really good, thunder can be good (you usually should miss your self though, avoiding damage to yourself), side b is good for recovering and punishing a puff that missed a rest, UpB is supah sexy.
another thing that will help you with your range problem is Perfect Agility stuffs. you can approach with agility as long as your opponent isn't in a postition to punish it or don't see it coming and then you can just upsmash them or something.
but really for killing i find it best for Pichu to just try to get gimpy edgeguardyness. you have quite a few attacks that will get them off stage (back throw, fsmash, nair, bair, etc.) then you can follow up with a nair or jolt off stage or you can fsmash/dsmash/upsmash them out of their upB or w/e. Falco/Fox are an easy kill if you can get them bellow you. i usually charge up an Fsmash then let it go right as they begin to move and it kills them.
you can also jab to edgeguard if you do it fast enough
if you get fox or falco in the right position you can do your fair and it will drag them down bellow the stage and you should be able to grab the ledge before them if they are still able to get back.
Nair off the ledge is also good for gimping if you've grabbed the ledge.
sorry for this wall of text, I'm just typing everything that I can think of that I do to get kills...
And I too share your affinity for Low tiers ^^