题目内容：
根据前面第一、二大题和以下业务背景资料，回答相关题。2008年4月23日，福建新隆进出口有限公司外贸业务员赵萍填制好保函申请书，备齐相关资料，并交纳全额保证金，向中国银行福建省分行申请开立保函。2008年4月25日，中国银行福建省分行通过审核，同意福建新隆进出口有限公司开立保函的申请，内容如下：
LETTEROFGUARANTEETo:LKFootwearInc.DateofIssue:Apr.25,2008 No.876WalkRd.,Vancouver,CanadaDearSirs, Re:OurIrrevocableGuaranteeNo.9999 WehavebeeninformedthatFujianXinlongI/ECo.,Ltd.(hereinaftercalled“thePrincipal”)hasenteredintothecontractNo.XL0798datedApr.22,2008withyou,forthesupplyofPacBoots. Furthermore,weunderstandthat,accordingtotheconditionsofthecontract,youarerequiredtomakeanadvancepaymenttothePrincipalofamountUSD22320.00,being30%ofthetotalpriceagainstanadvancepaymentguarantee. Thisbeingstated,we,BankofChina,FujianBranch(address:No.136WusiRoad,Fuzhou,350003,China),herebyirrevocablyundertaketopayyou,uponyourfirstdemand,anysumnotexceedingUSD22320.00(Inwords:UnitedStatesDollarstwentytwothousandthreehundredandtwentyonly.),uponourreceiptofyourdulysigneddemandforpaymentinwritingstatingthatthePrincipalisinbreachofhisobligation(s)underthecontract. Forthepurposeofidentification，yourwrittenrequestforpaymenthastobepresentedthroughBankofChina(Canada),VancouverBranch,(SWIFTCODE:BKCHCATTVAN)confirmingthatthesignaturesthereonarelegallybindinguponyou. ThisGuaranteeshallonlybecomeeffectiveandoperativeoncetheabove-mentionedadvancepaymentisreceivedbythePrincipalintotheiraccountNo.80020002700605302heldwithus. Thisguaranteeisvaliduntilthe3rdmonthaftertheeffectivedateofthisguarantee.Theguaranteeshallautomaticallybecomenullandvoidifyourwrittenrequestforpaymenttogetherwithabankconfirmationofyoursignaturesisnotinourpossessionatouraboveaddressonorbeforethatdate. ThisGuaranteeissubjecttotheUniformRulesforDemandGuarantees,ICCPublicationNo.458. ThisGuaranteeshallbegovernedbythelawofChinaandallpartiesareheretosubjecttothejurisdictionofthecourtsofChina. ForandonBehalfof BANKOFCHINA,FUJIANBRANCH _________________________ AuthorizedSignature(s) |
（1）该银行保函是属于哪一类保函？分别在何时生效和失效？（3分）
（2）如果福建新隆进出口有限公司未能按合同规定的期限发运，且不能及时退还预付款，则会产生什么后果？（2分）
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