For lager type kits stick with "noble" hops (Hallertau, Tettnanger, Spalt, and Saaz) as those are the traditional lager hops.
Be careful with the terms used in hopping as they might not quite be what you think they are...
You could be mistaken for thinking that dry hopping (aroma) won't alter the taste/flavour of your beer. It will. Considerably. You could be mistaken for thinking that late additions in a non-kit boil or a hop tea won't do a lot for the smell of your beer. It will. To a degree at least.
The terms bittering, flavour and aroma, when it comes to hops are base groups of chemicals that have an effect on "taste" and "smell" (I'm using the quotes there as taste has only four components: salt, sweet, sour and bitter; which are detected on the tongue, all other complexity in the enjoyment of food and drink is essentially smell although it gets to your soft palette from the back of your mouth rather than up your nose so REAL flavour is really a combination of taste[tongue] and smell[soft palette] and aroma just smell - so I've used the quote to differentiate from the real meanings without using the words flavour and aroma which would be more confusing).
Bittering refers to the alpha acids extracted and isomerised during the long boiling process and which give dry, bitter notes to the "taste" of your beer.
Flavour refers to the heavier (physically more dense) aromatic compounds in hops which are extracted more easily than the alpha acids but boil off after 30 minutes or so. These tend to be the deeper more "vegetal", grassy "tastes" and to a degree smells but being heavy and not very volatile they don't evaporate from your glass easily. You'll get a lot of these from a boil of between 15 and 30 minutes.
Aroma refers to the lighter (physically less dense) compounds in hops which are extracted very easily but boil off really quickly. These will be your citrussy and floral notes in both "taste" and "smell". You'll get these from a short boil of 5 minutes, a steep like making tea, or for the most "zingy" effect by dry-hopping.
To my mind for a lager you probably want the flavour and some aroma so try boiling some hops for 20 mins and add some more with 5 mins to go.
How much? No idea... you are completely off-piste at this point, there are no guides or software packages to work it out.
If I think back to kit brewing days, my biggest available pot would boil 8 litres (a jam pan), working with that I would say maybe 15-20g for 20mins and add 5-10g for the last 5 mins and use the resulting liquor to make up your kit.
Give it a go!