Not sure exactly where you are getting those items you listed from, as they do not appear to be from any single specific table from 5800. Therefore any answers I give could be wrong, as I am attempting to interpret the question from a jumble that is mixed together from various locations.
Let's try to take them one at a time.
Failure involves no danger XP x 0,5 (isnt fumble a Danger? It killed one of my PCs once)
The only mention I see of "Failure involves no danger" is where it is listing XP multipliers on page 71 in regards to maneuvers (static and moving). That section applies ONLY to maneuvers, it does not apply to combat OR spell casting, as those two areas have their own XP sections.
In any case, failure in casting a spell DOES involve danger (the same for combat), so this would never apply to spell casting or combat.
PC is in no Danger: XP x 0,5
The only listing I see talking about "PC in no danger" comes from page 72, where it says "Spell Caster is in no danger". What that means is that the caster is not being threatened in any way, shape or form.
Routine XP x 0,5 (can casting a spell becomme routine? like imbedding a spell in rune paper quite often ... etc)
makes for a 10. lvl Mage casting a 10. lvl spell 12,5 XP instead of 100 XP
Routine XP x 0.5 seems to come from the first paragraph under 23.1 Experience Point Multipliers on page 71. The second paragraph gives a description of what could be considered Routine. The end result is that it is up to the GM to make that determination.
But the short answer is -- Yes, casting a spell CAN become Routine if you make a routine out of it.
Is hitting something with a Wapon routine for a Figther?
Is using a directed spell instead of mele little or no danger?
Combat has its own section. But yes, combat against a SPECIFIC type of creature can be routine, but I wouldn't go as far as to say that combat in general can be considered routine.
