1. What does the church want to hear?
It really does depend on the church and how soundly evangelical it is (and I can appreciate this word may have a different connotation in the States) iand how interested in missions the church is. Some churches just want you to fill a gap in the programme or as an interlude in a series on Romans whilst other churches want some light entertainment.
But assuming the church is supportive of missions, they want to hear you being honest about your situation. They like to hear of your ups and downs; of family news; of projects you are involved in and people you work with. Obviously somethings can't be shared and you also need to be sensitive. They like to understand what you are going through so they can pray more effectively.
I have also found churches like to be challenged about missions and their involvement in missions. Mission is not just for others, or for the zealots, but for you.
With reference to cih3155's point "Do you think it was necessary to bring that up? Does the congregation need to know that he doesn't usually preach before large audiences?" Yes that is important as that is the situation the missionary is actually in. We may belong to large churches but many misionaries are working amongst small struggling groups in mud huts, in rented halls or in someones living room
2. What doesn't the church want to hear?
If the church is supportive of missions then I really think there is nothing that it doesn't want to hear. The problem arises with church that are not really interested in missions. Some liberal churches equate missions with health care and social relief. If you work in an RC country they think Catholics are Christians anyway and you are just a bigot.
Whenever I went to a church I just preached and may have illustrated the message with examples from the missionfield. I can think of a few times when irate (and probably unconverted) people came to me afterwards objecting to what I said. I would not be arrogant in any way but I believed I was teaching what the scriptures taught.
3 & 4. Good things missionaries say or stress/bad unhelpful things
-When missionaries acknolwedge their work is done through the local church. They are there to either plant a local church or develope the local church and that all outreach, disciple making etc is done through the local church even although the missionary may be a "foreigner".
-When missionaries, although leaders, are there to serve the local church and to recognise the local church is better placed (although possibly lacking resources) than a foreign mission board.
-When missionaries acknowledge other groups, not of their camp, are doing a good work. I recall hearing someone a year or two back who spoke saying there were no Christians and no churches for many miles from the town he was working in. What he really meant was there were no baptist churches for some distance. I knew the area and there were in fact a number of Presbyterian, Brethren Assembleys and other independent churches. But because none were baptist he gave the impression no one else was doing anything.
-I never like it when missionaries just come and say we need money for this and money for that; it puts me right off.
5. What do churches expect?
This is similar to point 1
6. Questions arising
I don't really know, I was always on my way home!
7.Alarm bells
I have already mentioned the money thing and from points 3 & 4 I am always wary of those who are not working with a local church. I am always concerned where the missionaries home culture interferes or even despises local culture or where local culture is just written off. It can be dificult I know but the gospel transcends all cultures. A British or American missionary should not be planting a British or American style church in Africa, Asia or wherever.
I have big alarm bells sounding where the missionary is projecting an image to suit the congregation. Sometimes false impression are given in order to increase support. Sometimes literature produced by mission agencies is like a press release in order to please the mission supporters. I recall meeting a minister who was involved in an agency. The workers would post monthly reports to him for a magazine. He edited the reports to such a degree that the reported situation in the magazine was quite different to the reality of the situation the missionaries found themsleves in. It as basically painting a rosy picture for the benefit of the supporters.
8. Good/bad speakers
I have found captivating speakers have been the ones who have fed, challenged, encouraged, rebuked and inspired me. Not because of dramatic stories but because of the way they ministered the word.