"Yes" to the first question; "no" to the second.
First, there seems to be some level of conventional wisdom that lawyers do not make good witnesses. I do not concur with that. As third party witnesses, I regard lawyers as better than average witnesses. I understand that the public sometimes has negative views toward lawyers. But if a lawyer takes the stand as a third party witness, the general tendency of jurors to believe a witness unless circumstances strongly militate to the contrary kicks in. Moreover, lawyers generally are better skilled at expressing themselves than the average person. They are also less likely to fall into traps. As all trial lawyers know, there are many types of evidence that are, in effect, double-edged swords--it helps in one way, hurts in another. Lay witnesses are more likely not to see the trouble coming from the negative side.
Professor Kingsfield, in the movie "The Paper Chase," famously said that beginning law students started with "a head full of mush" but ended their three years "thinking like a lawyer." Of course, not all lay persons have heads full of mush. But there is enough of an element of truth to this to say that a lawyer/witness is more likely to be able to finesse the "negative" side of the double-edged swords. They have more presence of mind about that sort of thing.
The second question asks about lawyers as defendants, but the same considerations apply to lawyers as plaintiffs. Here, the public's relative antipathy toward the legal profession has more relevance. I would not describe it as white-hot anger toward lawyers. Rather, jurors simply tend to be much less forgiving of lawyers for mistakes or misconduct than they are for non-lawyers. It seems to be an attitude of "ok, you're so smart--you should have known better." Probably for this reason, I have found that lawyers defending legal malpractice cases tend to be less willing than the average to allow a case to go all the way to trial. This is not to say that lawyers cannot win as parties; they can, but they have a somewhat heavier burden.