causals, imperatives, and other questions

[LaVonna Funkhouser <lffunkhouser -at- HALNET -dot- COM>]

~~~~~~~~  I posted this request to copyediting-l also.
~~~~~~~~  Forgive me if you receive it in both lists. LF

Please help me and the editing team with these questions.

1.  _Because_ is best at showing a causal relationship, but
    is _since_ ever appropriate in technical writing?  What
    about this sentence, which I think is showing a condition:

    Since/Because water is always in the process of dissolving
    or depositing solids, potential scale formation must be
    continuously addressed.

2.  Is _having_ stronger or better in this phrase, and if so, why?

    wells with scaling tendencies
    wells having scaling tendencies

3.  Are hyphens needed in these class names when the noun "scale"
    is not present, as in this example:

    Scale types can be divided roughly into three classes:
    - Water soluble
    - Acid soluble
    - Acid insoluble

4.  Last but not least--Is the comma necessary/unnecessary or
    recommended/not recommended when two imperative statements
    are joined?

    Keep this in mind when recommending Product and make the
    operator aware of this characteristic.

Because my problems may bore others, please
reply to me: lffunkhouser -at- halnet -dot- com -dot- 

If your red pen itches to make other changes to these sentences,
go ahead, but please reply directly to me.

TIA,
LaVonna   lffunkhouser -at- halnet -dot- com
++When intelligent editors disagree, the one with Internet
  access seeks advice!!++