1. Based on my chart what kind of spouse will I get? I know I have Cancer in 7th house cusp and ruler moon is in 11th house Sagittarius that is trine with saturn, venus and mars. What does it show about him?
Your chart doesn't spell out who you'll marry or what they'll be like, but it does show, in very rough outline, what kinds of qualities you need in a partner. You're most likely to be attracted to people with those qualities, and when it comes to choosing a spouse, you choose someone you're attracted to, so it's going to be someone who has those qualities.
Cancer suggests someone who's nurturing. Maybe also someone who has a homemaker bent--not that they necessarily are a homemaker, but they probably enjoy at least some aspects of creating a home, and can provide that for you. Maybe this is someone who likes to cook. Maybe they create home wherever they are. Maybe they're the one to decorate and arrange the furniture.
Sagittarius suggests something Sagittarian about this person. Maybe they're a foreigner in some sense: born in another country, or from a different religion or ethnicity than yours. Maybe they like to travel, and take you along. (Maybe you yourself really like to travel, with that Sag moon.) Maybe they're very optimistic, happy-go-lucky, take each day as an adventure. In some way, this would have to be someone who feeds the Sagittarius in you.
Eleventh house suggests community, groups, common causes. Perhaps you need a relationship with someone who shares a common cause with you. Perhaps you meet them through a community group or endeavor. Perhaps you start a new one together.
While Venus and Mars are in your seventh house Placidus, they're in your eighth whole sign, so I'm inclined to look at where the meanings of seventh and eighth house overlap. The seventh is the relationship as it's defined and recognized by others (husband and wife, boyfriend and girlfriend, etc.), while the eighth is the undercurrents of it (emotional connection, sex, shared resources, merged finances). Mars and Venus are the sexual planets... you probably need the sexual side of your relationship to be very strong, and would never stay in a sexless one. Since Mars is the masculine principle and Venus is the feminine one, that could also be read as being attracted to people who are androgynous in some sense--maybe in looks, maybe in personality. But only you know if that's true for you.
2. When are the upcoming transits and months or years in my chart that can point to me meeting a potential spouse in the future?
That question could be a reading in and of itself. Predictive astrology is very complex, and there are no hard and fast predictions that can be made through birth charts, at least not with any guarantee of accuracy. There are windows of opportunity when relationships are more likely to start, if you're looking for one or at least open to one, but every window of opportunity is a potential opportunity for more than one thing. What looks at first glance like a relationship opportunity might play out in a different way. The reverse is also true: you might find a relationship when you don't think the astrological conditions are that favorable. It's easier to see the relationship triggering transits in hindsight than in advance.
That said, I've heard on here (and seen in my own life transits) that it takes Jupiter to get you interested and Saturn to get you committed. If you meet someone you're interested in when both Saturn and Jupiter are making significant transits to your chart--their own natal positions, or your angles, or your sun, moon, or personal planets--that's when the potential for it turning into a long term relationship is greatest. Right now, and til the end of this year, Saturn is dancing with your ascendant, and you reflect this by being ready to commit to a relationship and getting serious about looking for one. You also have Jupiter squaring your sun/Mercury, which could open that window of opportunity, and if it doesn't happen now, you'll have a Jupiter return in January, which is another strong Jupiter transit.
December and January will also see a pair of eclipses (lunar and solar) along your first/seventh house axis, with one of the eclipse points being right on your natal Jupiter. That's another potential for relationship, due to both the houses they fall in and your seventh house being ruled by the moon and eighth by the sun.
So you have a strong potential for entering a serious relationship this winter, or maybe even sooner. That doesn't necessarily mean you'll marry this person, but the potential for long term is there when Saturn is so active, and if long term means marriage to you, then the odds of that happening are up.
And if you don't find someone serious then, the transits will open some other kind of opportunity for you. You might even already be seeing the other opportunity(s).
3. How will I meet my spouse?
Impossible to say. Birth charts don't provide that information.