umbrellas, kiddush, snow and elevators

i have saved up my hilchot shabbat questions, only to unleash them all at one go:

1. umbrellas -- chabad doesn't carry them even if there's an eruv. the chap told me you can't carry one "because of ochel." i don't know anything about ochel, but um, really??
2. on shabbat day, my brother (who was not keeping shabbat and was already in the middle of his meal) saw that i was getting ready to do kiddush for myself and offered to do it for me. i didn't know if his kiddush would really be valid (for the reasons listed in parentheses) and didn't know what to do. what should i have done?
3. shovelling snow/ice off the walkway - yes or no? does it matter if it's being done to promote safety or not?
4. elevators -- our doormen have been instructed to call the elevator for us and press the button for our floor. (on the way down, we take the stairs.) is this ok, or do i need to start hauling up nine stories?

thanks, in advance, for your answers.

ANSWERS:
Thank you for your excellent questions. Here are some answers.
1. umbrellas are not allowed. This is because the Nodeh b'Yehuda didn't allow them. He felt opening an umbrella was like building a tent (ohel). It is difficult to understand his reasoning, since it should be more similar to a folding chair (which is permitted) than a tent (which is forbidden). Even though we don't really understand why the Halacha should be like this, it has been accepted by all of klal yisrael around the world, and therefore his p'sak is now binding. Even on yom tov it is not permitted, and even if you opened the umbrella before Shabbat started and left it open you are still not allowed to use it.
2. Whether or not your brother could say kiddush for you is an interesting and complicated question. However, women have exactly the same obligation as men in kiddush, and therefore in this case it is more appropriate for you to say it than him. Why not take the equal opportunity bit when it presents itself.
3. If there is no eruv shoveling snow may involve issues of carrying. In addition it may be considered building or destroying (depending on whether you make the ground smooth underneath - less of a problem if the snow is on asphalt or concrete). There may also be muktze issues involved. Also, it is tircha (exertion) which is not ideal on Shabbat. Therefore if it is not essential it would be better not to shovel snow, unless it is a real hazard. Putting down grit or salt would be a better solution (though it may also involve muktze issues unless you set it aside before Shabbat). Walking on it and kicking it to the side is fine. If it is very dangerous it seems to me that it should be permitted to shovel if there is no alternative (but isn't that part of the job description of the doorman mentioned in the next question?).
4. The Aruch says that asking a non-Jew to do things on Shabbat is permitted for the sake of a Mitzah. Provided you are going to do the mitzvah of eating a Shabbat meal, of having a Shabbat rest or something like that perhaps there is room to be lenient (since we don't normally rely on this Aruch). There is also the health issue that 9 flights of stairs may be good for your lungs, but it may also be bad for you heart until you get used to it (and it certainly isn't good for your oneg Shabbat). There are certainly opinions that you can rely on.

Thank you for your questions. Looking forward to some more.
Rabbi Sedley