No, the uses you describe are probably illegal. Touching the green to test it or touching the line of the putt are illegal and so is leaving a club on the green when the stroke is made.
Rule 8-2b bars "indicating the line of a putt":
b. On the Putting Green
When the player’s ball is on the putting green, the line of putt may be indicated before, but not during, the stroke by the player, his partner or either of their caddies; in doing so the putting green must not be touched. A mark must not be placed anywhere for the purpose of indicating a line of putt.
Rule 16-1a prohibits touching the line of the putt, with certain exceptions that don't apply.
First, this Decision is relevant:
Hey Rules Guy: During a match, my directionally challenged opponent used a club to help him take better aim. He'd place a club on the ground to help get the correct alignment, then toss it aside before hitting his shot. Isn't this an illegal aid?
– Lou Maiatico, via e-mail
I feel for the guy, Lou— it's easy to misaim in this game. (If only clubs came with those handy-dandy hunting-rifle scopes!) In fact, using a club as a temporary directional aid isn't against the Rules. Under Decision 8-2a/1, your opponent's use of the club is permissible, since he removed it before making his stroke. Now, had he forgotten to remove the club, he would have been penalized two strokes in stroke play or with the loss of the hole in match play. Although the relevant rule is different, that same penalty would apply to a Tour pro whose caddie, having (legally, under Rule 14-2b) helped the boss align, forgets to move himself from an extension of the line of play or putt behind the ball before the player makes the stroke. Remember: Ready, aim, remove…fire!
Club Placed on Ground to Align Feet
Q. A player places a club on the ground parallel to the line of play to assist him in aligning his feet properly. Is this permissible?
A. Yes, provided the player removes the club before playing his stroke. Otherwise, a breach of Rule 8-2a would occur.
Notice that using an "aiming stick" to do the same is illegal even if the player removed it before the stroke, since this is an "artificial device." Rule 14-3.
This Decision applies to aiming sticks:
Use of Rod During Round for Alignment or as Swing Aid
Q. During a stipulated round, may a player use a rod or similar device to check his alignment or his swing plane?
A. No. The player would be using an artificial device or unusual equipment to assist him in his play in breach of Rule 14-3. Carrying the rod or similar device is not, of itself, a breach of a Rule. (Revised)
(See below for more on reconciling Rule 8-2 and Rule 14-3.))
Object Placed Beside or Behind Ball to Indicate Line of Play
Q. May a player place his pipe or a club beside his ball, or an object behind his ball, to indicate the line of play and leave the object there while playing a stroke?
A. No. Such action would be a breach of Rule 8-2a.
Even if not otherwise illegal, using a club in an abnormal manner to help play the stroke violates Rule 14-3:
Rule 14-3 bars use of artificial devices and use of clubs in an abnormal way:
2. A player is not in breach of this Rule if he uses equipment in a traditionally accepted manner.
So-called "plumb bobbing" is an abnormal use of a club that villates 14-3 except it has been deemed "traditionally accepted." Not so with laying a club down on the green.
As usual, the USGA folks aren't all that bright and have created some confusion. By allowing the use of "a club" as an alignment aid so long as it is removed before thd stroke, under Rule 8, while deeming use of an "aiming stick" per se illegal as an "artificial device", under Rule 14-3, tgey have apparently ignored the "abnormal use" of equipment (such as using a putter in plumb bobbing). Placing a club down as an alignment aid should be deemed "abnormal" and therefore an "artificial device" just the same as an aiming stick. If so, removing it before the stroke doesn't avoid the penalty.
If you prefer SKILL, both uses are illegal. But IMHO the USGA is very often "askeep at the switch" and not too bright. The whole tangle of Rules and Decisions pretty much proves my point.